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Wayne Gerdes - CleanMPG.com (www.CleanMPG.com) - June 21, 2006
Pulse and Glide

Let me take this opportunity to thank Dan Kroushl (Krousdb) who taught me the Pulse and Glide technique for Prius II’s last year. I also want to credit my “Prius Marathon” friend and co-driver Dave Bassage and Internet friend Bill G. for their help in making P&G one of the most important tools in my own hypermiling toolbox. Both Hobbit and Graham Davies should be credited for discovering/describing “Warp Stealth”. Doug Schaefer for taking the time to clean up and brigten some of my less then spectacular pics. And finally Carl H. for both his time and the use of his Prius II for many of the pictures below.

First 100 mpg Prius II segment

http://www.cleanmpg.com/photos/data/506/First_Sustainable_100_MPG_Segment_in_the_Prius_II.jpg
Krousdb’s first ever recorded 100 mpg + sustained segment in a Prius II

A friend of mine from work, Carl H., used to receive the upper 40’s/lower 50 mpg’s in his 2005 Prius II from the time he drove it off the lot through late spring/early summer of last year. With what I was taught in regards to P&G via E-Mail from Dan, Dave, and Bill, I passed along the technique as I understood it to Carl and his FE went from that higher 40’s/low 50’s mpg mark to the low to mid 60 mpg mark seemingly overnight! As his Prius II has broken in, temps have warmed in Illinois again, his Prius II’s setup is almost perfect, and he has become more adept at using the P&G technique in situations where it would be applicable, he is now punching out 70 and 80 mpg tanks over his own 25 + mile commute! His use of an alternate route paralleling the Interstate has allowed the ability to run within the P&G constraints for much more of his commuting distance allowing him to almost but not quite double his FE from Day 1 until today! With these real world results, I hope you can both learn and use the technique(s) when and wherever applicable in your Prius II as well.

Prius II
http://www.cleanmpg.com/photos/data/506/Carl_H_and_his_Prius_II_on_his_Warmup_P_G_route_through_Forest_Preserve.jpg
Carl H. and his Prius II on the Alternate - Warm up Pulse and Glide Route.

Without further fanfare, here is the P&G and “Warp Stealth” technique(s) in both explanation and with pictures so you can learn from and use them while driving through your daily grind as well.

Pulse

“Pulse” is any acceleration from a lower speed target at a rate to keep from drawing off the pack while also filling the pack (Green Arrow from the MGSet to the Pack on the Energy Monitor screen). You do not want to see Orange arrows from the MGSet to the Wheels on the Energy Monitor screen. Our intent during the “Pulse” phase is to get up to a top target speed less then 41 mph in which you can quickly and smoothly transition to the “Glide” phase. Any top speed target will work to fit a given traffic condition as long as you maintain less then 41 mph for the highest FE. That was the explanation but how do you actually “Pulse”?

Using a 30 mph to 40 mph band as an example, when you are cruising along at 30 mph, you step into the accelerator just enough so as to not see assist from the pack (as described above) and fast enough to maintain an average “Pulse” rate of your choosing. You can control your “Pulse” rate of acceleration but you do not need to maintain an exact rate as seen in the pics below. A 20 mpg average “Pulse” rate may include an initial 17 mpg rate when you first start the “Pulse” and maybe 23 mpg “Pulse” rate when you hit your top target speed before you transition to “Glide”. For a 40 mpg average “Pulse” rate, you might see a 36 mpg “Pulse” rate when you begin your “Pulse” and a 44 mpg “Pulse” rate just before you enter your “Glide”. To recap, you gently step on the accelerator enough to get the ICE to spin up and provide propulsion with the energy screen showing ICE power to the wheels and power through the depicted MGSet to the pack while the digital iFCD readout is showing anywhere between 15 and 55 mpg for the acceleration back up to 40 mph or less.

Proper Pulse

http://www.cleanmpg.com/photos/data/506/Pulse_Rate_of_16_1_mpg.jpg
Example of a 16 mpg Pulse rate.

http://www.cleanmpg.com/photos/data/506/Pulse_Rate_of_23_3_mpg.JPG
Example of a 23 mpg Pulse rate.

http://www.cleanmpg.com/photos/data/506/Pulse_Rate_of_32_3_mpg.JPG
Example of a 32 mpg Pulse rate.

http://www.cleanmpg.com/photos/data/506/Pulse_Rate_of_40_5_mpg.JPG
Example of a 40 mpg Pulse rate.

Glide

“Glide” is the coast down mode that can be a bit tricky. What you want to see in your Energy Monitor screen is the ICE-Off and no arrows from anywhere or too anywhere (Black Screen) while you are coasting down from the top “Pulse” target speed to the lower target speed for a given traffic condition. This allows little to no loss of momentum via Regen or providing “Electric Only” propulsion to the wheels. The way the “Glide” technique is implemented is that you hit the maximum target speed below 41 mph during your “Pulse”, let off the accelerator just a touch for a fraction of a second to shut down the ICE and induce a touch of Regen (best if you can skip Regen altogether), then press down on the accelerator ever so slightly to achieve and then maintain blacked out arrows all around with the ICE shut down, no regen to the pack, and no pack to MGSet to wheels propulsion down to the lower speed target. The blacked out arrows on the energy screen tell you that you are in or very close to being in this almost coast free state. You will need to practice this in your Prius II as it is not intuitive. I am sure most have probably been told by whomever that Regen is a hybrid’s real technological advance. It can be in circumstances when you must come to a stop before you had planned without the ability to “Glide” much of that distance. Many hypermilers evoke Regen for SoC management, when confronted with an uncontrollable slow down during a heavily congested traffic situation, or when a blown light timing forces an abrupt stop. Just remember that a pure “Glide” from 40 mph and below as well as “Warp Stealth” as described later on in the article from much higher speeds works. With a little practice, you will be able to enter into and out of “Glide” mode at will while just using your right foot on the accelerator.

Proper Glide

http://www.cleanmpg.com/photos/data/506/Proper_Glide.JPG
What a Glide will look like on the Energy Monitor screen.

You may consider using a small amount of EV to maintain a slower speed and or crest a small peak so you can continue your glide down the back side. There are limits to EV so use it sparingly within the P&G technique and only where it can extend your Glide for even higher FE.

Why does P&G actually work? P&G is not just about a speed range nor is it about an acceleration rate. It is a combination of a given amount of fuel consumed and distance traveled in the “Pulse” phase vs. the distance traveled in the “Glide” phase. If you “Pulse” for .3 miles at 35 mpg, you need to “Glide” at least twice the distance covered during the “Pulse” (.6 miles) to achieve 105 mpg average over .9 miles. When “P&G” is broken down to its component parts and reassembled, you simply have to accelerate for a given distance at a given consumption rate (“Pulse”) and coast (“Glide”) for an extended distance to cover the Pulse’s fuel consumption to achieve a given FE. Here are a few examples:

The following equation will show you what you will need to achieve for a given target FE.

Pulse distance * [(Target FE mpg/Average Pulse Rate in mpg) – 1] = Glide distance needed to achieve target.

For a 100 mpg target goal, the following equation and examples of differing Pulse rates (Average FE during the Pulse) will give you your glide distances needed to achieve your 100 mpg goal!

Pulse Distance (miles) * [(100 mpg/20 mpg) – 1)] = Glide Distance (miles) needed to achieve target.

Pulse at a 20 mpg rate of acceleration over .2 miles:
.2 miles * [(100 mpg/20 mpg) – 1] = .8 miles of Glide to achieve 100 mpg over a total distance of 1 mile.
.2 miles of Pulse at a 20 mpg pulse rate with .8 miles of Glide will give you a 100 mpg.

Pulse at a 30 mpg rate of acceleration over .3 miles:
.3 miles * [(100 mpg/30 mpg) – 1] = .7 miles of Glide to achieve 100 mpg over a total distance of 1 mile.
.3 miles of Pulse at a 30 mpg pulse rate with .7 miles of Glide will give you 100 mpg.

Pulse at a 40 mpg rate of acceleration over .3 miles:
.3 miles * [(100 mpg/40 mpg) – 1] = .45 miles of Glide to achieve 100 mpg over a total distance of .75 miles.
.3 miles of Pulse at a 40 mpg pulse rate acceleration with .75 miles of Glide will give you 100 mpg.

Pulse at a 50 mpg rate of acceleration over .4 miles:
.4 miles * [(100 mpg/50 mpg) – 1] = .4 miles of Glide to achieve 100 mpg over a total distance of .8 miles.
.4 miles of Pulse at a 50 mpg pulse rate with .4 miles of Glide will give you 100 mpg.

Pulse and Glide sequence in the real world

Pulse

http://www.cleanmpg.com/photos/data/506/23_8_MPG_Pulse_Sequence_1_Photo.JPG
Prius II “Pulse” Sequence #1: RR Crossing sign is ~ 1/3 mile ahead. Time is 11:38 AM. “Pulse” rate: ~ 24 mpg. Speed is ~ 33 mph and climbing when the picture was taken. Pulsed to ~ 35 mph due to (2) sharp turns after RR tracks ahead. Notice 3 Blue Bars on the SoC graph.


Glide

http://www.cleanmpg.com/photos/data/506/Glide_Sequence_2_Photo.JPG
Prius II “Glide” Sequence #2: Notice RR Crossing sign a hundred + yards ahead. Time: 11:38 AM. Proper “Glide” showing no Arrows. ~ 33 mph and decelerating slowly in the “Glide”. Notice 4 Blue Bars on the SoC graph achieved during previous “Pulse”.


Glide Continued

http://www.cleanmpg.com/photos/data/506/Glide_Sequence_3_Picture.JPG
Prius II “Glide” Sequence #3: Just about to pass RR Crossing sign. Time: 11:39 AM. Proper “Glide” showing no Arrows. ~ 32 mph and still decelerating in the “Glide”. Notice we still have 4 Blue Bars on the SoC graph for a little EV later on in the “Glide”.

To wrap up the tutorial on P&G, you want to accelerate up to a maximum of 40 mph in the “Pulse” phase, begin the “Glide” phase and coast down to a lower target speed. Once the lower target has been reached, you want to reinitiate the “Pulse” phase, re-accelerate back up to a maximum of 40 mph using the energy screen as displayed, and repeat when and where applicable. The Prius II is very flexible in terms of how to apply the P&G technique to a given traffic situation. You can “Pulse” at any rate between 15 and 55 mpg, “Pulse” to a target of 40 mph or any speed under that depending on what traffic allows, and “Glide” from the higher speed “Pulse” target to any lower speed including stopped! It only depends on traffic conditions around you. For most, a “Pulse” w/ a 17 - 23 mpg acceleration rate might be best to keep up with normal traffic acceleration rates and compress the P&G speed range to between 33 and 39 mph while driving on a 35 mph limited roadway or in traffic tie-ups and jams that allow it. While P&G’ing between a 33 and 39 mph range, a car behind on the 35 mph limited roadway can barely perceive you are driving any different then they might be themselves! P&G will push a Prius II’s average FE over a given distance through the roof when and where it can be implemented. The large band and lower target speeds may make the P&G technique un-usable under a multitude of traffic and or roadway conditions you may drive through on a daily basis. When in those non-P&G friendly conditions, drive as any hypermiler would with only a portion of the tools available and save the P&G technique for when and where it can be applied safely and correctly.

Normal Commute Result

http://www.cleanmpg.com/photos/data/506/81_5_MPG_-_492_miles.jpg
Carl’s current tank at 81.5 mpg after 492 miles going back and forth to work.

Interesting 5 minute bar graphs above. First 5 minute bar: Country road transition to a short State Route jaunt. Second 5 minute bar: Short State Route and transition to country road. Third and fourth 5 minute bar’s: Country Road. Fifth and Sixth 5 minute bar’s: Heavily traveled city/suburban roads with ~ 90 mpg average over the 30 minutes. Carl's previous record tank may be bested by 8 mpg's and possibly more? Still at 1/2 tank too!

Warp Stealth or HS (High Speed) Glide

What is the “Warp Stealth” technique all about? Since I personally have < 20 miles in a Prius II at highway speeds, I can only describe what I saw on the Energy Consumption screen while exiting the Interstate multiple times early yesterday afternoon. Carl has been using this technique for a while to great advantage when under higher speed conditions. I was astounded seeing it for the first time with the ICE-Off under a type of EV mode while far above the 41 mph MG1 limits. Hobbit lightly touched upon the technique a few weeks ago in the thread entitled Throttle Control (http://www.cleanmpg.com/forums/showthread.php?t=915). MG1 is spinning backwards at a very high RPM as it should in this condition. Warp Stealth is very similar to the HCH-II’s EV/Glide mode in which the ICE is spinning while in Fuel Cut. With a slight amount of EV, you can slow the deceleration somewhat but a HS “Glide” is where the Fuel savings will make this technique a good one for those traveling the highways and byways of America. The 2 pictures below should explain exactly what you will see while the Pack draw is minimal when coaxing the Prius II into this condition. For a more detailed description, please read Hobbit’s page on: “Warp Stealth: a Prius driver's guide. (http://techno-fandom.org/~hobbit/cars/warpstealth.html)”.

Warp Stealth

http://www.cleanmpg.com/photos/data/506/Warp_Stealth_Full.jpg
Prius II Full Picture - We were decelerating through 48 mph at the time I snapped the picture while coasting down onto the off-ramp from a short highway jaunt. This is “Warp Stealth” or HS “Glide” while exiting I-55 in North Central Illinois.

Warp Stealth - Closeup

http://www.cleanmpg.com/photos/data/506/Warp_Stealth.JPG
Close up of the Prius II’s Energy Screen during the “Warp Stealth” mode above. Although the cloth is covering up most of the Speedometer, you can just make out the side of the 4 and top of 8. This is the same image as above zoomed in to the area of interest taken while decelerating through 48 mph showing 99 mpg, ICE-Off, and running down on EV. This is what “Warp Stealth” or a HS “Glide” looks like close up.

To enter into “Warp Stealth” from a higher speed cruise, you drop back on the accelerator a small amount and enter into a slight slowdown with a very light amount of Regen for fuel cut. Skip the Regen just as you do when entering “Glide” if at all possible. The Energy Screen should show an ICE-Off condition. Slowly reapply the accelerator (exactly like you would to enter “Glide”) which eliminates any Regen if you did inadvertently evoke it. You should see the pack come online to keep the ICE (still in Fuel Cut) spinning yet off at a rate to protect MG1 and/or help push the car via MG2 a small amount.

How can “Warp Stealth” be exploited besides for a high speed “Glide” (41 mph and above) and transitioning to a std. “Glide” (below 41 mph) while coasting down to an arterial from a Highway Off-ramp? I have the distinct feeling “Warp Stealth” can be exploited similarly to P&G below 41 mph but at highway speeds? A HS P&G may be an area some Prius II owner would like to explore. I am positive it will not yield the same types of FE increases as a standard P&G below 41 mph will but you may see a nice increase over and above the Prius II’s standard higher speed cruise. This higher speed cruise is where the Prius II begins to consume fuel at a rate some may consider unacceptable and especially when compared to its capabilities below 41 mph? I will leave this question open until either Hobbit or another serious Prius II hypermiler can take the technique to its final conclusion.

Finally, please practice the technique(s) above on roads with little to no other drivers around until such time they are second nature. There is a risk you will be paying far too much attention to the Energy Monitor display while learning/practicing instead of the road ahead as you normally do! I am sure we all know what the consequences of this inattention could lead too so please for all our sakes, be very careful out there.

Good Luck

Wayne

I have played with the concept of trying to P&G at higher speed
using WS for the glide part. It's sort of frustrating because
at interstate speeds, the dropoff is much faster due to air
resistance. Trying to punch it pretty hard to get back up to
speed [2500 - 3000 rpm] seems to suck enough gas to defeat the
whole effort.
.
What I'm working on now is a more steady state, but with better
RPM control that still decently loads the engine. Minimizing
RPM but not allowing manifold vacuum to climb appreciably is
returning marginally better results than other things I've tried,
I think, but more data are needed.
.
At the upper end, there's some magic stuff that happens around
2400 rpm that other people have observed too. I suspect that the
VVTi starts to change to a more "power" state, letting less of
the Atkinson compression/expansion difference remain in play. So
I'm trying to limit RPM to 2200 or thereabouts, which still gives
barely enough oomph to climb gentle rises at 55 - 60 with a
nominal slowdown in the process. Staying in that range, from
maybe 1300 to 2200 rpm at the widest, is my current theory and to
really know what's going on I'm going to have to start digging a
little more data off the CANbus.
.
Still, a modified P&(WS) technique seems to kick ass on those
annoying 45 - 50 mph speed limit roads where you can't pure
P&G but it's not quite fast enough to run steady-state ICE-on.
Even the limit-40 roads have enough buttheads on them expecting
you to go faster than 41...
.
_H*

Wayne,

Great job describing png in an easy to understand manner. The pictures are great because it gets across what drivers need to be seeing on their energy monitor without words getting in the way (and maybe being misunderstood). I think I am starting to get the hang of pulse and glide and have managed some 20 mile segments at close to 90 mpg, but I can't seem to get past 90. I think part of the problem is roads with speed limits of 45 to 50, I need to find a route with more roads of 35 to 40 mph speed limits.
If it were you (master hypermiler that you are) and there was no traffic to consider, would you choose the slower acceleration for your pulse in the prius (say around 50 IFE) to maximize fe or the faster acceleration (20 IFE) assuming flat terrain?

Hobbit,
I think I have said this elsewhere (but in case I forgot and only think I said it), your article on warp stealth is great! I have been trying to use this to boost fe at speeds between 40-55 mph. For those of us without canview or scangauge or some means of monitoring RPM can you roughly translate your ranges for RPM into ife on flat ground (I realize the ife will be different at 2200 RPM depending on whether you are going uphill or downhill and the steepness of the hill.) For example at 2200 on flat ground the ife might be 30-35 mpg but up a steep hill it might be 10-15 MPG at the same rpm. Thanks.

Dennis

Good point, and that's one thing I've been remiss in trying to
report -- the IFE while doing the experiments on the highway.
Well, I'm sort of still trying to work it out, so that's why I
didn't think to start spouting any numbers. But there is a rough
mapping... and IFE variance has more to do with your *speed*,
since if a given engine RPM/consumption happens to be moving
you faster, your miles per those little milligallons is higher.
.
Anyways, let's assume I'm going 60 mph. None of this hawk-the-
vacuum-gauge stuff seems able to push me any faster than 65,
so that's a good middle figure. Generally when I see the vac
start to appreciably rise as I let my foot off, the IFE is
floating anywhere between 60 mpg and 75. So I don't want to
get greedy and let it go higher than that -- it's easy to peg the
thing by letting off further, but now you're into more throttle
closure and lower torque, and you might as well warp-stealth
at that point. So let's say somewhere between 55 and 75 mpg.
On the high side, at 1800 rpm I see slightly less than 50, and
that seems to provide a reasonable power output to gently keep
accelerating on the flats, up to 65-70. Uphill I need to crest
2000 rpm at which point the IFE is down around 30-40 ... and
then if I head above 2300-2400 the vac drops further, and the
IFE lands pretty solidly down around 25 mpg. I try to only use
that for steeper hillclimbs. Of course every so often a hill
comes along [but generally not on interstates around here] that
needs 3000+ rpm even to crawl up, but seriously, I don't really
demand any more than that and that still keeps me on par with
any truck that might be attempting the same climb. In other
words, an acceptable amount of power for the weight of the car,
in this case about 40 hp that I rarely go beyond in demand.
That should tell us something about the amount of power the
american redneck *really* needs...
.
_H*

Hi Dennis:

___Thinking along the lines of longevity first, the 50 mpg Pulse makes more sense to me as it is far less stressful on components then a sub 20 mpg one. Not that a sub 20 one is stressful either ;) If there were no one anywhere near, I would expand the range to improve P&G FE and not worry so much about the rate. I have experienced the 5-minute bars pegged all the way across the 30 minute screen at 50 + mpg Pulse rates and sub 20 Pulse rates so it really doesn’t matter. As long as you have the road to yourself, expand the range and the FE will come to you rather then you chasing it ...

___The 45 - 50 mph type limits you are encountering severely hampers ones ability to maintain FE in the 90’s in a Prius II as I am sure you are well aware. I find myself looking back when I leave the Warm up P&G route and wishing for more just as I am punching it back up into the mid 60’s range for the next hour of open Interstate :(

___Good Luck

___Wayne

Thanks for the excellent description, Wayne. I found some of the images too dark (on my monitor at least), and have brightened up 9 of them with PhotoStudio. I am uncertain how to post those images back here so that you may incorporate them into your document if desired. Advice please.

DAS

tochatihu can no glide mode be acheved with your car? i'm curious to know

Wayne,

Just so I am clear, when you suggest expanding the range to improve fe, are you referring to the speed range? Instead of 33-39 mph, try 20-40 where time and traffic allow this to be done safely? Thanks for the advice.

Dennis

Hi Dennis:

___If you can, go ahead and expand the range. 20 to 40 might be a bit large for most roads but if no one is around, why not? I would think a 25 - 37 mpg range would be a good solution for a 30 - 35 mph limited roadway so as to not cause too much trouble on both the low side and the high? You know, speeding and all ;) Out on a desolate road, the throttles are wide open.

___Another key to the huge numbers is working your local terrain with a small amount of EV within the P&G (LS, std, or HS) technique to extend Glides. This is also an area where “Warp Stealth” may be able to kick up the highway FE in the Prius II? I HS P&G the Accord quite a bit throughout much of Chicago’s Interstates to vastly improve her highway FE (not by comparison to a Prius II, HCH-I, or II mind you) and this area of IL. is not known for being hilly. There are enough rises and falls on most roadways in most states to take advantage of this situation and thus my question about taking advantage of Warp Stealth at highway speeds far beyond what Hobbit may have considered to date? I would love to get my hands on a Prius II for a week of my mostly highway commute to figure this one out :D

___Tochatihu, when I get off night shift in 3 days, I will send you the final rotated/leveled, cropped, and re-sized pics as well as the RAW originals so you can play with them at your leisure. It was so bright during the limited testing that the pics posted are some of the better ones after I lightened; changed contrast, and Gamma levels on some of them already.

___Good Luck

___Wayne

Hi Philmcneal, gliding is definitely possible in the NHW11 Prius. It is simply that I am not very good at the whole range of FE techniques. One thing that I intend to do is switch to weaker return springs in the accelerator pedal. But my supply of spare accel pedals keeps getting depleted. I repair the failed ones as a hobby.

Wayne I don't know if I can work with RAW images. JPG is the most familiar.

Hi Tochatihu:

___I meant RAW jpg’s (in the original format with no editing). You can work with those, right ;)

___Good Luck

___Wayne

Yes I can. RAW image files are quite another thing.

DAS

Hi All

Great article Wayne, this helps others having a hard time understanding P&G. Every car I drive, I see an increase in FE using P&G now. It’s like learning how to avoid the brakes, but you learn how to limit the gas pedal in addition.

Unless the Prius does not have a wheel end or center axle disconnect, I can’t see that deadbanding would be preferred over neutral for the glide. It may be possible to check the Prius owner’s manual for the towing requirement restrictions. If they advise it’s ok to tow in neutral, there may be an axle disconnect like the FEH.

Higher P&G speeds will never yield you better FE than under 40mph, but they are better than no P&G at say 70mph. P&G is always in the cards for me at any speed. It’s all in the management of how to limit the use of the gas pedal and coasting or gliding. So what if at speeds of 70mph you slow faster, your going to yield better FE over pushing a constant speed of energy because you demanded less during coasting time.

Every condition requires adjustments in our daily grind, P&G is part of the tools I use thanks to the people here responsible for P&G.

GaryG

Hi Gary:

___Thanks for noticing ;)

___The Prius does not have a driveline disconnect like the FEH does in N from what I have been told. There are two individuals named in this article that have done the coast down tests and they end up at the same approach speed after so many tenths of a mile using either before creep takes over :(

___As for Deadband, this is a description of “only” power flow to the wheels via the ICE (not the MGSet and back to the pack) during a “Pulse” in Prius circles. I never really liked the term or the ability to see/achieve it so I left it out of the discussion so as to not confuse anyone. The std. “Pulse and Glide” as described is the real “killer app” approach to maximum FE in the Prius II. The FE from “P&G” works so well that I can only hope most Prius drivers will add the P&G technique to their toolbox ASAP.

___Although this article is not about the TCH, that thing is another completely different animal when it comes to P&G. It not only has a higher RPM capable MG1, MG2 is also geared via another gear set for even higher torque output at higher speeds. Another neat thing and one I have wanted to see for years is a very light Regen on accelerator let off vs. the std. wham, you are in a full blown Regen slow down from highway speeds. The TCH just barely kisses Regen until you actually start grabbing the binders. Another item I felt first hand after being told about it is the TCH is very tough to place into a pure “Glide” state w/ a lower SoC and at higher speeds. I wish I would have had more then a few minutes in one on my own route without all the weight to take it to its possible conclusion :( With that, I would not rule out a lengthy 100 mpg segment from one sometime in the future. I think it is capable but the TCH will have to be dropped into N for her own version of pure “Glide” to achieve a real coast free state just like the FEH. In other words, it does have a driveline disconnect in N from what I felt as I dropped her back into N within the last 30 seconds I was behind her windscreen of my short test drive. I wish I would have known about this before I had sat down in the drivers seat to get a bit more out of her even though she had < 1,000 mile on the odo …

___An additional item … Because of our 2 hours of taking pics and pushing Carl’s own Prius II for the article, I gave him some pointers on the return loop to improve upon his already spectacular tanks. With that, he is now successfully running 95 - 100 mpg segments from home to work and back vs. the 70 - 80 mpg segments previously. Keep a close eye out for this guy in the coming months because I think he has a shot at the first 95 - 100 mpg tank in a Prius II (no small feat as all of us know) while simply commuting back and forth to work with the few additional tweaks to his technique we had the opportunity to discuss.

___Finally, I would like to tweak your FEH article somewhat when it cools down in your locale later this year. What I would like to do is add some additional pics of the NAVI’s - Energy screen during the different phases of FEH LGA-N-D for EV ops as well as add a video loop with appropriate commentary to describe it even better. Maybe I can take a trip down your way w/ the digital camera and video recorder to lock it all down in late fall when it cools off. I was reading over my older Word Documents describing the Prius II specific P&G before I wrote this article and came to the conclusion I probably buried more people in detail then helped. For this article, I decided to capture on camera a very specific grouping of pics (P&G in the Real World Sequence), very exacting pic’s of the various “Pulse” rates, “Glide”, as well as “WS” as it was actually seen during the event(s). Although my pics were of poor quality, I believe it is much easier to understand the what’s, why’s, and how’s from the pics now vs. the excessive verbiage I had used in the past to describe the same technique(s) in other areas of the web. I would like to do the same for your FEH the next time we get together so as to help current and future FEH owners understand how the LGA - N - D for EV and FS is accomplished.

PS: Great thread on maintaining your FEH’s FE while using A/C to keep you and the pack at a much more comfortable temp given your location too!

___Good Luck

___Wayne

Hi Wayne,

If you have not been sworn to secrecy by Carl, could you share some of the pointers you gave him? Undoubtedly there are others (me for instance) who are making some of the same "mistakes" as Carl was (I can occasionally pull off an 85-89 mile segment over 20 to 40 miles), the occasional highway or short errand trips kill my overall tanks.

Today I had a eureka moment (inspired by your article) while driving up a long hill. In your article you emphasized the distance of the pulse and the distance of the glide. I have often made the mistake of thinking in terms of the time spent with the ice on vs ice off. This would lead to hard acceleration at say 20 mpg so that I could spend less time with ice on and more quickly reach the ice off glide. This might make sense on flat ground and would also make sense going downhill, but going up a long hill it is unlikely that one can reach the ice off state for any length of time. If the ice will be on over the distance of the hill (call it x) why not go as slow as traffic and time will allow and get maybe 40 to 50 mpg over the distance x, rather than trying to get to some target speed like 40 mph more quickly and maybe end up with an average of 20-25 mpg over that distance x. Once you reach or get close to the crest of the hill you can use a little ev to get you to your target speed if SOC allows or once reaching the crest you can let gravity take over if the hill is steep enough, if not use a little more ice or ev to get to your target speed and then glide. You have often stated that lower rates of acceleration are your preference, and for hill climbs I am definitely seeing this, I think on the downhills and the flats acceleration at 35-40 mpg up to target speed works well. Another observation is that target speed should be adjusted down at the top of a hill because gravity will often take you up to speed relatively quickly so if your target speed is 40 only use the ice to 35 or so (depends on the steepness and length of the hill).

Dennis

Hi Dennis:

___What I explained to Carl is to move into and out of the 2 states a bit quicker and hold the “Glide” longer by widening the range. I noticed his accel rates were slowing as he approached the higher target speed and thus he was ICE-On for a longer period then he needed to be. I also guided him towards using EV at the bottom of the range a little longer so as to extend the “Glide” distance as well as use it to crest in a decal to regain speed on the descent. You have already discovered this last item by the latter portion of your reply. Given the way EV works, you want to transition to “Glide” before you crest, bleed off speed to the lower target and then EV over the crest for a full “Glide” accel on the descent of whatever you are climbing. The last thing was to begin the “Glide” a bit further from a known stop so as to DWB. It wasn’t much but when you put it all together; he is now besting the 100 mpg barrier on a much greater portion of his route.

___We do not have the types of hills on Carl’s Alternate Warm-up P&G route where DWL can help much within the P&G technique but in any climb, I would DWL to a mid speed target, transition to “Glide”, bleed off speed to the lower target, then EV over the crest giving away kinetic for potential smoothly. After the crest, your newly gained potential can help you back to a nominal speed with ICE-Off for the illustrious extended “Glide” we are all looking for.

___There are other tools so as to reach the illusive 100 mpg segment goal but it involves swapping back and forth between the Energy and Consumption display or having a Yoshi supplied SuperMid connected. I would prefer most simply keep the Energy display up so as to transition between “Pulse” and “Glide” smoothly and efficiently with the least amount of distraction. 100 mpg will be in their future if they can find that section of road or traffic condition that allows the technique to be exploited to its final conclusion.

___Good Luck

___Wayne

Wayne,

I really appreciate that you take the time to answer my questions, hopefully there are others besides myself who will benefit from your tips. I mostly use the energy monitor and occasionally check consumption to see how I am doing. In order to check how my individual trips are going, I use the method you employed with Carl's Prius when you first tried pulse and glide in the prius last summer (I am a fan of yours in case you couldn't tell), so by noting the avg mpg on the consumption screen before and after a trip and recording the number of miles of the trip I can calculate an approximate avg mpg for the total trip (I only reset when I fill up). Other than this I am not sure how one would use the consumption screen except maybe to see where the 5 minute bars are (occasionally I get 2 consecutive bars at 99.9) or to see if the avg mpg is increasing or decreasing, it is not that hard to take a quick check in the middle of a glide or at a stop light, the hills tend to prevent me from maintaining the high mileage, but I am going to try some of your tips and I'll let you know how it goes. I finally checked Carl's stats over at green hybrid, I would agree with you that pretty soon he will be giving Dan K, and Lakedude a run for their money, 76 MPG may be the best tank ever, (besides Dan) in a Prius. No doubt he will surpass Dan's 86.7 tank soon and Dan will have to take the Prius back from his wife. I can't imagine what you would be able to achieve driving a prius all the time.

Dennis

I'm gonna resurrect this thread as being most appropriate to present
a VERY PRELIMINARY version of my "prius sweet spot" writeup,
http://techno-fandom.org/~hobbit/cars/sweet/
I wanna bounce this one off you guys and get feedback/tomatoes
before calling it finished and spamming the Prius-lovin' world
with what I hope is the answer to all their prayers.
.
_H*

Hi Hobbit,

Great writeup. I have been struggling with FE at speeds over 40 mph and especially on the highway, so this is exactly what I have been looking for. I usually manage around 55 mpg on the highway at average speeds of about 63 mph, I have tried using warp stealth and high speed p&g but at highway speeds I usually do just as well with cruise control and switching to high speed glides on the downhills.

I have no added instrumentation (I am thinking about a scangauge or supermid m1) so I will need to base my technique on iFCD until I add something to show me vacuum and RPM. You suggest staying between 35 and 75 mpg on the iFCD, I assume 35 would be going uphill or accelerating and 75 on slight declines or flat ground once up to speed and obviously 75 would be better than 35 all else being equal. What is not intuitive is why iFCD readings between 75 and 99 mpg would actually result in a lower overall mpg than say 60 to 75 mpg. Is this because you would not be at an optimal point on the Torque vs RPM curve (with the RPM being too low) when above 75 mpg instantaneous? I often strive for the highest possible iFCD readings without realizing I might actually be hurting my avg mpg (except when in high spped glide), it is counterintuitive, but I certainly will give it a try because I would be quite pleased with 63 at 63. One thought is that by staying higher on the torque curve and getting up to say 65 or 66 mph, you can then go into high speed glide and let the speed bleed off to say 59 or 60 mph and then pulse back up to 62 mph or so at say 40 to 50 impg (instantaneous mpg) on flat ground and then let up a little on the throttle and try to keep it at 70 impg. If you continue to accelerate up to say 66 mph then let up a little more and go into high speed glide down to maybe 58 mph or so. Is this what you have been doing? I realize you are basing your throttle position on your sweet spot meter, vacuum gauge, and rpm and not so much on iFCD, but a little more detail on how to approach this technique without extra gauges would be of interest to many. It sure looks like the scan gauge is going to be my best bet to try and nail this thing. Thanks again for sharing your findings.

Dennis

Hi Hobbit:

___I had planned to create a thread about this in the tech section given it could get controversial … The reason why is because we are going to be in a debate of sorts here.

____Rick Reese took his Prius I to a 70 + mpg tank using a simple Graham scanner. He found two areas where higher FE could be achieved while only concentrating on the load section and built in iFCD. IIRC, it was something like a 25% and a 70% load area (load being ??? on the Graham Scanner) where the magic appeared.

___Because you have had little to no time behind the wheel of an IMA equipped Honda hybrid and its superior instrumentation; you will find various throttle position that not only increase FE but maintains a given speed. All Honda IMA drivers actively seek out and ride this slight less throttle position while maintaining the highest FE per the iFCD possible at a given speed. Hot Georgia has spoken of this many many times in the past in fact but you can usually gain 5 – 10 mpg’s just by following the iFCD … The same should hold true in the Prius I/II. Set it up and continually adjust to get that aFCD to max for a given speed. I think you may be limiting yourself by burying the details inside your gauge package. Just a thought but if you give a Honda Hypermiler the Prius II for a week, he/she will seek out and find the same using the Consumption display’s iFCD but will be varying the TP as road conditions, traffic, and weather/temperatures vary.

___Good Luck

___Wayne

You've mentioned Rick and his miniscanner experiments before.
I went looking around a little bit -- found some results at
Greenhybrid, not IC, and it helps a whole lot to spell his name
right... so Wayne, please check
http://www.greenhybrid.com/discuss/showthread.php?t=452 [also t=459]
and tell me if that's the thread you were thinking of -- and if
not, I would really appreciate if you could dig up the specific
reference. I found *nothing* at Insight Central.
.
In the meantime, I've asked Graham how he calculates %load. The
OBDII garbage I have from Alex Peper seems to be calculating
it way higher than is reasonable, and claims a 23% load during
*warp stealth* f'krissake when the engine is being DRAGGED.
So it's becoming really important to me to learn exactly where
some of those old numbers are landing.
.
I don't think you can quite apply the same "throttle setting"
methodology to an eCVT. The throttle control basically does
what it needs to, quite decoupled from what your foot is doing.
I will point out that when the Prius opens the throttle quickly
like it does, it is not to *full* -- in fact the ballpark opening
appears to be 20 to 25 percent, as claimed by OBDII and also as
measured as a fraction of the full voltage swing of the TPS pot.
So it is quite possible that the Prius is already doing your
"lower throttle opening" game, and saving the full-throated roar
for when the driver really punches it. My quest is to optimize
best use of that "gentle" region.
.
One thing that may help with understanding HSD, within certain
confines, is that pushing harder with your foot has the effect
of selecting a lower gear ratio. This is totally non-intuitive,
but given what I see with RPM in relation to wheel speeds in
a scenario where the throttle opening largely remains UNCHANGED,
that's got to be how it works. RPM goes up, power [thus hill
climbing ability] goes up, but all within that narrow range of
engine *torque*.
.
_H*

Hi Hobbit:

___Here you go: OBDII Scanner (http://www.insightcentral.net/forum/viewtopic.php?t=1352).


For my commute (No battery only operation due to too high a speed) I found the % engine load, RPM, % throttle, and amperage in/out of the main battery the most useful items to keep in the main display. Keep in mind this is my first attempt. Anyway the scanner is mounted on the steering column as Graham recommends and its a nice design (even adjusts the backlighting with a light sensor automatically). For the Prius driving for efficiency is a bit different than the Insight. Since it is an automatic with a variable gear ratio you can't shoot for a specific rpm. The % engine load however directly correlates to fuel economy. As a result I looked for a % engine load that provided a high fuel economy yet was high enough to accelerate on down hills and gradually loose speed on the up hills without the engine lowering the drive ratio. I found an engine rpm of 1300-1400 seams to be best for fuel economy. I found too good ranges. The first was a 32-36% engine load which would produce 90 mpg values on the instant bar graph at 1300-1400 rpm. In areas with hills however the engine would lower the drive ratio on hills which would drop the fuel economy as the engine rpm hit 1700-2000 depending on the hill. The better range in hilly areas was around a 45% engine load. This would give a instant value of around 75 mpg at 1300-1400 rpm. At this load however you would maintain a higher average speed and might hit 75-80 on a down slope. The kinetic energy however would allow you to crest most hills with the rpm still around 1300-1400 so you don't drop to the 25 mpg range when the engine gears down. I should mention that I took my throttle control rope out of the Insight and put it on the Prius for the trip. Interestingly enough the same % throttle did not always yield the same % engine load. (I was usually around 19-23 % throttle) but the engine load was not consistent given the same terrain.

I was thinking if we could get enough orders perhaps we could persuade Graham to build one of these scanners for the Insight. I think the amperage in/out of the battery could be very useful in determining the best fuel economy range. In other words balance the trickle charging with discharging. If I set the tension on my rope too tight the Insight will drain the battery over say 30-50 miles but if I set it just right I can cover the areas in the foothills without depleting the battery and let it charge back up on the flatter sections.

Have fun, Rick
___% Load with the SG-II is not a great way to measure ICE load either. Running a max 19 - 20 TP (10 to 89 min/max) at maybe 1,900 RPM in a nice and easy Pulse shows ~ 65% load in the Accord. In other words, pretty useless other then as an instantaneous type load gauge.

___When I speak of a throttle setting, I am not speaking of maintaining a particular throttle setting or TP set point but DWL using the iFCD as the guide. I do not really care what the ICE is doing internally if I can instead maintain focus on an iFCD to maximize FE no matter the car. As long as the iFCD is a real world number or at least closely follows the actual iFE, I should be able to maintain it at the highest level for any given speed … Unfortunately, most of my Prius highway driving experiences arose while sitting in the passenger seat watching you or Dan driving your own Prius II’s :(

___Good Luck

___Wayne

Okay, thanks; I must have still been using the wrong name to
search at IC. The greenhybrid post is almost equivalent with fewer
specifics.
.
I'll note that 1300-1400 rpm at 22% or so TPS and upwards of
75 MPG on the iFCD [only at interstate speeds, it's always lower
if you're going slower] is at the *low* end of my "sweet spot
range". Very minimal demand. It also corresponds roughly to
your "40 mpg pulse rate"...
.
This stuff shouldn't be that different between Prius I and Prius II,
I would think... but I've never actually driven a Classic,
especially armed with a vacuum gauge...
.
_H*

Is there anyone here with an SG-enabled Prius that could try
a couple of things for me? Mainly, accelerate from a stop while
keeping RPM at, say, 1600, and take note of what the SG reports
as % load during that. It will probably vary a bit but I'd like
to know the ballpark of what SG thinks your ECU thinks.
.
Ideally, I'd be able to get this data for both a Classic and a
3rd-gen and see if there's any difference.
.
_H*

Okay, I updated http://techno-fandom.org/~hobbit/cars/sweet/
with a little more explanation, and less of a "do exactly this"
feel in favor of a "we might be onto something here but more
research is needed" theme. With more silly pictures. Please
give it a look and let me know what should be added. What *could*
be added is a whole book about hypermiling at the bottom, but
I'll leave that to Wayne!
.
In the meantime, I got an answer from Graham about the miniscanner.
His %load figure is simply grabbed from whatever the ECU says
about it. However, if a gen-3 Prius is at a claimed "35% load"
that's completely useless for maintaining any prayer of highway
speed, so there might be something else going on here that may
be peculiar to the Classic.
.
_H*

Hello, Hobbit. I've been fascinated with your findings regarding this sweet spot ever since I stumbled upon the article on your site. I don't have a mechanical or engineering background (I consider it a major accomplishment just to have changed the oil myself!), so I've read and re-read it to try to absorb it. The take home lesson seems simple enough: At speeds above those where P&G is useful, use “warp stealth” when conditions allow, and when they don’t, in the Prius with no added instrumentation, keep the instantaneous MPG between 35 & 75. I’ve been doing both whenever possible.

I now have more instrumentation available: I just bought a used ScanGauge I. I've set the SG to display RPM so I can can watch that. But not fully understanding what many of the other SG parameters are, I'm not sure what else to use to help approach Prius high-speed FE utopia. Are you familiar with what it can display? If so, which of the other parameters would be best to monitor in order to achieve and maintain this sweet spot, and what numbers should I aim for?

Is there anyone here with an SG-enabled Prius that could try
a couple of things for me? Mainly, accelerate from a stop while
keeping RPM at, say, 1600, and take note of what the SG reports
as % load during that.
_H*
Did you get what you need in response to this? If not, I'll offer to test this and anything else you might need with the SG.

BTW, I posted a similar message on PriusOnline, so if you've responded to one, you may disregard the other unless you think it worthwhile for the masses reading the thread.

Thanks!

In the meantime I've gotten hold of a Vetronix Mastertech MTS3100
to borrow, i.e. the official Toyota tool, and if *that* lies to
me then something's very wrong. Under most fairly gentle
acceleration scenarios I see about 50% calculated load.
I'd still be interested in what your SG says...
.
I rarely hang on priusonline these days; mostly on priuschat,
well, until it got knocked over AGAIN and I hopped on POL for
the updates.
.
_H*

Hobbit, thanks for the reply. I remember someone else suggesting 50% as a max. I think it was in CleanMPG, but I can't remember. I've searched in so many places, I can't remember what I've read where. :confused:

Anyway, for your acceleration test, how long/fast do you need me to hold that RPM?

I knew you were pretty consistent on PriusChat, but it was still down when I posted on POL. There's now a nearly identical post on PC.

Thanks again!

Hello,
I would like to hear some comments about Prius fuel injection at downhill coasting on highway.
Discussing on PriusOnline, they say ScanGauge tells them 110 - 200 MPG instead of 9999.9 above 42 mph.
http://www.priusonline.com/viewtopic.php?t=9236&highlight=

Our Japanese Prius clearly shows the fuel cut, but they say some fuel is consuming for CAT.
Maybe, it is cause by the emission control system difference on the US models.

I believe the ScanGuage is a kind of macro type of instrument and it sometimes lies. :)
Can anyone confirm this using oscilloscope or anything?

Thank you,
Yoshi

I wanted to throw my 2 cents in here since I just spent >100 miles on the highway in the closest thing to a HS P&G cycle that I could manage.

First let me address Yoshi's question about the ScanGauge showing fuel injection while the Prius coasts downhill. In reality I don't think the ScanGauge knows how to deal with fuel cut while the engine spins. While I was watching its iFCD in the Accord it became apparent that the device isn't looking at actual fuel injected. Instead, I think it's basing its calculation on engine displacement, RPM, and manifold absolute pressure. I have never, ever seen 9999mpg without cutting the engine completely. 5MT Insight users will attest to the fact that it can't handle lean-burn, either, which would not be a problem if it had a way to monitor injector pulse width and had some idea of the injector capacity. (Doesn't the SuperMID look at the injectors directly?) I can't confirm that through any instrumentation but this is what the empirical evidence tells me.

Finally, what I experienced last night. It turns out that the Prius II responds a whole lot better on the highway than I would have expected. Yes, a 1.3L lean burn i-dsi engine with a tall 5-speed would blow this guy out of the water. But coming down the back side of every hill in Warp Stealth gets the job done. My concerns of draining the pack were completely unfounded, as the SoC was completely stable at the top-most blue bar even after a mile+ in the 60mph range. (The only time I have seen a lower SoC so far was after an extended EV at ~30mph around town.)

However, I do think that I pay some price for gliding down those hills with the engine being spun by MG1 (I think?). It looks like the ECU has figured out my game and likes to keep the battery topped-up in anticipation of my next demand for current. The result is that there were a few times when I would have expected >60mpg at a cruise but it was hanging in the 40s instead. After a minute or two it's back to its old self, especially if I throw in a little regen for speed control and to help it along.

Barely 300 miles on her and that 105 mile segment came out just north of 56mpg in 43F temps while travelling at an average of 60mph. The Prius II is a joy to drive in this kind of aggressive cycle since it responds so well to fine accelerator input. I'm very much looking forward to seeing what she can do with 5,000+ miles on her and some spring-like daytime temps.

Hello all,

I am the proud owner of a new 2007 Prius Touring (Pkg. #3) for 4 whole days and counting. (Yay!) This online community of "Prii People" and technical information is kind of overwhelming, but it's great for newbies like me to have resources to go to.

I'm averaging 47-50 mpg on my 35 mile each-way commute. It's mostly through small towns, on back roads, and on state routes, but it's hilly. So far, I'm quite pleased and I'm finding this mileage thing quite addictive.

Here's my question, though. Is my car a Prius II that you speak of? (I was told that my car is the 4th generation of the Prius that Toyota has made?) Can I follow the same rationale/procedures listed in this thread? I've tried coasting techniques down hills and on flat sections of road and I can't get the display to show no energy flow arrows. My Prius has the Hybrid Synergy Drive and the CVT transmission. I think it might be behaving differently than models with prior generation technology, but I dunno.

Thanks much!
dyoungerman

Hello all,

I am the proud owner of a new 2007 Prius Touring (Pkg. #3) for 4 whole days and counting. (Yay!) This online community of "Prii People" and technical information is kind of overwhelming, but it's great for newbies like me to have resources to go to.

I'm averaging 47-50 mpg on my 35 mile each-way commute. It's mostly through small towns, on back roads, and on state routes, but it's hilly. So far, I'm quite pleased and I'm finding this mileage thing quite addictive.

Here's my question, though. Is my car a Prius II that you speak of? (I was told that my car is the 4th generation of the Prius that Toyota has made?) Can I follow the same rationale/procedures listed in this thread? I've tried coasting techniques down hills and on flat sections of road and I can't get the display to show no energy flow arrows. My Prius has the Hybrid Synergy Drive and the CVT transmission. I think it might be behaving differently than models with prior generation technology, but I dunno.

Thanks much!
dyoungerman
Welcome to CleanMPG and congrats on your purchase, dyoungerman! The masters (not me, though I'm working on it) are here to teach you!

Yes, yours is what many refer to as the Prius II, which began with the 2004 model year. It's actually the third generation, which leads to confusion as you've seen. Here's a good overview (http://www.cleangreencar.co.nz/page/prius-history) of the Prius models' history. To eliminate confusion in discussions where multiple models are discussed, many use the actual Toyota model numbers, NHW10, NHW11, and NHW20. IMHO, just stating your model year is sufficient.

I don't know all the differences between the Touring model and the basic model, but the hybrid propulsion system is the same. I'm sure the Touring package could affect fuel economy in small ways -- different tires, for example -- but I believe you should still get good hypermiling results if you apply what's taught here and on the Prius forums.

In particular, keep working on your glides. As long as you're at 40 MPH and below, completely let off the pedal for a second or two, allowing the ICE to shut down and green arrows to appear, and then feather the pedal ever so slightly until the arrows disappear. Once you're able to call that up on demand, you're on your way. If you can't safely stay at those speeds, then at higher speeds "warp stealth" produces mostly the same effect. The technique is the same. The visible difference is that you won't provoke a "no arrows" state, and instead the slight pedal feathering produces orange arrows.

It takes practice and patience with these and many of the hypermiling techniques described on this site. I suggest you take a couple of them at a time, get good at them, and then progressively add more. I've had my car for over a year, and it's been only recently that I've started even to come close to what the experts have done.

About time to bring this thread back to life ....

I've been wondering something recently: With the experience we Prius drivers now have under our collective belt, is there a consensus on optimal P&G speeds and ranges? And a related question: Are there inefficiencies in the ICE starting and stopping during P&G? It would seem intuitive (to me anyway) that there would be.

Wayne's experience (described earlier in this thread) suggests wide P&G speed ranges get better results than narrow ones. Inefficiencies in ICE shutdowns and restarts would help explain his results. On the other hand, I remember Diamondlarry suggesting recently that he was experimenting with narrower speed ranges (5 MPH??), but I didn't see any report of his conclusions.

I began some controlled testing last year on various combinations of P&G speeds and ranges:

15-25 MPH
15-30 MPH
15-35 MPH
20-30 MPH
20-35 MPH
25-35 MPH

The tests were never completed because of the unanticipated need to replace my tires partway through. I plan to begin testing anew sometime this spring, and will include comparisons to steady-state driving. (Results will be posted.) But the incomplete results suggested that range had no effect; instead, results improved as the overall average speed dropped.

So, what's the current thinking among those of you smarter than me? ;)

Hi Jim,

I think this would be a great study. Maybe I could participate with you. If you give me the parameters you are using (distance, terrain, etc.) I could duplicate your efforts and we could duplicate the data.

Now that I have a scangauge, we could duplicate things such as tps and ign.

About time to bring this thread back to life ....


Wayne's experience (described earlier in this thread) suggests wide P&G speed ranges get better results than narrow ones. Inefficiencies in ICE shutdowns and restarts would help explain his results. On the other hand, I remember Diamondlarry suggesting recently that he was experimenting with narrower speed ranges (5 MPH??), but I didn't see any report of his conclusions.



So, what's the current thinking among those of you smarter than me? ;)

:oOops!:o I did mention that didn't I.:o I will be doing some driving on Monday and I may be able to test that out. Today, I was experimenting with 25-35 or so on some country roads. I also did a little bit with 30-40 or less. I did notice that the lower end target speeds that were closer to 30 mph seemed to have a higher impg number, ie. going from 30 mph or above to 35 mph or so. I went from my mom's house to a Sunday School class party that was a distance of 13.3 miles and, at ~40F I ended up with 82.2 mpg. Now, if I could just remember exactly what I did...:confused::D

I have a little story that is slighty off-topic for this thread but is related to mpg. When I got to the party, one of the guys asked me, "What kind of mileage are you getting in your car, 60 mpg?" I just smiled and said, "Maybe on a bad day.:D" Then they looked at me in shock when I told them that I may drive a little slow but I did get 82 mpg coming here. That brought on a short discussion on my P&G techniques; very short.:(

I'm posting from my phone so I've only skimmed the topic revival.

Now i have done some work this winter on shutoff and ice light losses. all done at lower speeds with am ev button.

On steady state I think ign14 should stablize around 70 mpg @ 46 mph. i think that will be the best.

if you test below 45 mph it well need to be done over many miles with start soc = end soc. If you get good numbers by canniblizing soc its invalid.

11011011

I have found on my highway trips to Chicagoland and beyond that when the speed drops much below 50 mph that the IMPG numbers usually start to fall. At 50-55 the number will bounce around from 80-85 or greater but will drop to the 70's when below 50 mph.:confused: They really start to drop off when below 45 mph. It must be that when rpm's stay the same that a higher speed will cause a higher calculated FE number. There will, of course, be limits to this because of aerodynamic drag if the speed is too high.

New Prius owner. thanks for all the info. this is gonna be fun to incorporate.
________
AnalDreams21 (http://www.girlcamfriend.com/cam/AnalDreams21/)

About time to bring this thread back to life ....

I've been wondering something recently: With the experience we Prius drivers now have under our collective belt, is there a consensus on optimal P&G speeds and ranges? And a related question: Are there inefficiencies in the ICE starting and stopping during P&G? It would seem intuitive (to me anyway) that there would be.


I have been wondering this since I learned about P&G.... Would it vary with the seasons also? I try to extend the P&G and sometimes I think I did too much as the ICE seems to get cold and does not want to glide.

I have been wondering this since I learned about P&G.... Would it vary with the seasons also? I try to extend the P&G and sometimes I think I did too much as the ICE seems to get cold and does not want to glide.


Slower is better than faster
Ultra low speed ICE-on is bad.
As few lights as possible is good.
Regen is bad
Assit is bad


DISCLAIMER: I use metric, so don't freak out.

OK... culling all that together, here's what I decided (the world according to 11011011). So basically we are asking the pulse entry point (at what speed you light the engine) and your glide entry point (at what speed you cut the engine). So looking at point 1, I decided that a low glide entry point was good. Looking at point 3, I want to have at least a 35 kph (21 mph) delta between my pulse entry and my glide entry velocities. Also looking at point 2 I don't want to dip below 20 kph (12 mph). So my "competition" window is:

Pulse Entry: 20kph (12 mph)
Glide Entry: 55kph (34 mph)

Now to satisfy point 4 and 5, I try to do all my pulse and glide transitions via an instantaneous EV switch (Radio Shack or Factory EV).

Now based on my SHM research, I really like to see my IGN around 14,15, or 16. So my pulse RPM is usually dialed in at 1600 RPM. Easy.

Outside of "competition" mode I bump my Pulse entry up to 45 kph (28 mph) or 30 kph (19 mph) if no one is around.

Hope that helps

11011011

I'm posting just to say that this is an excellent description of pulse and glide, and that I didn't really understand what the concept was until reading the first post. The glossary entry really should link to (or perhaps be replaced by) that post.

Hi Wayne and all HMs,

I come from Hong Kong and drive Prius for half year. This is a wonderful thread which teaches drivers to take the most advantage of Prius' parallel hybrid system in achieving FE.

I am still at learning stage and my reading increased from the original 45MPG (5.2L/100km) to 53MPG (4.4L/100km), certainly still a long way to go for even reaching the threshold of 60MPG! Given the nominal capacity of the fuel tank as 45L, here we each strive to make an own record of travelling 1000km with a full tank. To achieve this, one needs to be 4.5L/100km in theory for the very last drop of petrol. In practice, one has to be 4.3L/100km or lower. Not sure if there's any similar play for those in MPG.

To help me have some breakthrough in HM, here comes the questions:

- To start the car from stationary, the initial FE is terribly poor and FE improves gradually while the speed is increasing. So to avoid ICE on at low speed, I pressed the EV button for starting. When the speed reached 30MPH, EV would be off anyway. Bad point was the pack then probably left with only 3 or 4 bars which was not favarable for P&G and HS P&G. So now I used to start with EV button on but depress it when reaching 12-15 MPH, hoping to avoid the ICE starts from stationary, yet not to draw too much from the pack. Does this make sense in terms of FE?

- My parking space is on 4/F. So when returning home, I press EV button and drive up as fast and safely as possible. This usually left with 3 or 2 bars when parked. The next time I drive out, ICE usually turns itself on due to low SOC or temperature. But I am on the way down and hope that regen will rise SOC quickly while ICE is warming up. Again, does this make sense? Or should I better go up 4/F with ICE on?

- In warp stealth (HS P&G) gliding, the pack used to keep ICE spinning. In P&G gliding, if I press pedal slightly more, yellow arrow appears and it seems to help keep the speed. Is this really the case? So this time does the pack drive the ICE or keep it spinning?

Regards
Wilson

I understand that this forum is mostly for Prius owners but, is this pulse and glide something I can do with my 09 TCH? I have read this and am trying but am haveing a very hard time getting the screen with the power only going to the engine and the battery only? I see a lot of peopl have a scanguagII. Would this help me and if so how. Thanks, Rick

Hi Wilson:

___A good rule of thumb is to bring the Prius-II and –III up to 15-mph under EV and than bringing the ICE online. You can go higher but the SoC payback is harsh as you well know. I use 15 mph under most circumstances and it has proven its worth time and time again.

___End of the day SoC is a hard one. Here in the US, the ICE will start and not supply any power unless a high percentage of throttle is demanded. The Prius-II will accelerate on the pack and MG2 even while the engine is idling at 1,200 + RPM during to warm-up to achieve S1. It is absolutely ridiculous that it works that way but that is the way the Prius-II was designed for us here in the US to meet the strict emissions standards more than likely.

___During WS, the pack does indeed keep the ICE spinning over. It is a limitation of HSD to protect or limit current on MG1 when trying to start the engine while it is above 6,500 RPM at 41 mph. We have a technique we call Warp-Neutral wherein we engage N before we reach 41 mph and let it increase up to 62 mph (MG1 spinning at 10,000 RPM backwards) without the pack spinning up the ICE. This can only be used on downhill’s as you will not accelerate above 41 mph without the assistance of gravity.

___There are some limitations that can be exceeded with the above but that is best left to direct discussions with those in Japan that actually designed MG1 including its actual capabilities ;)

___Rickkop, CleanMPG is about all vehicles including all-electrics to 18-wheeerls. This thread is about HSD and your TCH can use similar techniques. To glide however, you will have to run N as the dead band is simply to small to control with your accelerator. If I ever get the opportunity to review a TCH (I really should get on this but Toyota has always been out when I have requested one), I will write-up a TCH specific technique section. You will be looking for 18 TPS and 18 IGN via a ScanGauge-II for 60 + mpg highway driving and using P&G around town with N to hold your glides is what it comes down to.

___Good Luck

___Wayne

Wayne,
I'm sure there a lot of us TCH owners out there that wish Toyota would get a TCH for you to review. Looks like if I'm going to be serious about mileage I better get myself a scanguage. Thanks for the help, Rick

Hi Rick:

___No problem and like I say to many TCH owners in person, you have one heck of a nice automobile and most importantly, enjoy it :)

___Good Luck

___Wayne

___A good rule of thumb is to bring the Prius-II and –III up to 15-mph under EV and than bringing the ICE online. You can go higher but the SoC payback is harsh as you well know. I use 15 mph under most circumstances and it has proven its worth time and time again.

This is only if you have excess SOC, e.g. 68 or 70 correct? And is this the optimal way to use the excess SOC?


___End of the day SoC is a hard one. Here in the US, the ICE will start and not supply any power unless a high percentage of throttle is demanded. The Prius-II will accelerate on the pack and MG2 even while the engine is idling at 1,200 + RPM during to warm-up to achieve S1. It is absolutely ridiculous that it works that way but that is the way the Prius-II was designed for us here in the US to meet the strict emissions standards more than likely.

I absolutely hate this. Even when the engine temp is say 190F from a previous trip, the engine will still behave this way, albeit for a much shorter time than the usual minute. Is it best to gun it up to 2200 RPM to bypass the excessive use of the battery or should you ride it out at very low RPM and very light acceleration so it won't take too much off the battery. I can sometimes lose 5 off my SOC in this phase if I accelerate normally. What is the best way to handle this?

Another couple questions I have is: should the pulses for P&G for rural 35mph driving be IGN 14? And using P&G + EV button from startup to get to S4 is not damaging to the ICE or any other components is it?

What are MG1 and MG2 as mentioned in the Warp Stealth section of the article? They don't come up when searched for a definition.

What are MG1 and MG2 as mentioned in the Warp Stealth section of the article? They don't come up when searched for a definition.
They are the two motor/generator units. Here (http://prius.ecrostech.com/original/PriusFrames.htm) is a user-friendly description of their design and operation (along with other aspects of Prius propulsion system function). Though the site describes the 2001-2003 model and some minor design changes were made in 2004, the MG concept and functionality are the same.

I have many miles in a 2006 Prius that was my parents. Because of the Clean Fuel plates and HOV usage, I left it in Northern VA with my sister whose husband has a bad commute and the HOV usage is key for him. I looked around and decided to get the Lexus HS250h. I am getting over 40mpg most of the time, but am finding that some types of fuel are much better for FE than others. Shockingly Chevron is about the worst so far. Probably another thread.

I had discovered the Glide on the Prius and used it all the time. Used to make my mom nuts as I would glide down to the turn for her house and w/o braking be able to make the turn. It was an over 55 community, so no-one gave a second look to a slow moving car.

In the HS250h I can't seem to find the sweet spot in the accelerator to glide.... I can feel what I assume from what I know about the Prius, the MG1 cranking down but find that it is very hard to release. It has a display that shows if you are charging or using batter (like a tach) and even using that have yet to find the glide.

Anyone have any ideas on why this is...it is the same system right?

Hi,

I'm a new member to the forum, hypermiling and Prius III ownership. What a great resource this site and some others have been. Looking forward to contributing as I learn & experiment.

Have been trying various techniques. With 4k on my 2010. For the last 1k am averaging 62.6 mpg. Have all tires at 44, what is the reason for suggested difference between front and back pressure?

Hi,

I'm a new member to the forum, hypermiling and Prius III ownership. What a great resource this site and some others have been. Looking forward to contributing as I learn & experiment.

Have been trying various techniques. With 4k on my 2010. For the last 1k am averaging 62.6 mpg. Have all tires at 44, what is the reason for suggested difference between front and back pressure?

Front heavy cars need extra pressure on the front tire.

I dont know if it was luck or not, but after reading this article last night I left for the gym. The battery's charge was pretty low and the engine was cool. I drove the Fusion 1.9miles to the gym at about 40mph. I was not able to get it into EV mode but it charged up the battery pretty good. The trip to the gym was about 31mpg. After spending 2 hrs at the gym I left for home, the engine had cooled down alot but the battery was charged up pretty good. I got the Fusion up to 40mph and then started my glide, It took me a few seconds to adjust the accelerator into the happy spot where there is no regen or use of the battery. Of the 1.9 miles home, I able to go the final 1.2 miles using no gas. I got 74mpg on the trip home. Maybe it was a fluke or good luck, but the 74mpg (my previous best on the home from the gym was 63mpg) has motivated me to continue trying the P&G method. The article was very informative and was very easy to understand. Xcel, can you direct me to other articles such as this? Plenty of info but easy for a hybrid beginner to understand? The "Beating the EPA" link on the home page is good starting point, but now I wanting more!

It definitely wasn't luck; there's a lot more available with some practice if the Fusion is anything at all like the Prius. I drove to our county fair today with all 4 of us in the Prius and all I really did was P&G from 40-30 mph and glide up to corners with stops and I was able to get just over 83 mpg on the 15 mile or so trip on mostly country roads. I probably could have squeezed 90+ out if I had tried real hard but I was happy with what I got since the last mile or less was stop and go getting into the fairgrounds.

Hi Delond2:

You are hooked and I am damn proud of you for it :)

And driving an FFH no less makes it all the more sweet!

Wayne

Thanks guys. I tried it again on my trip to the gym today. I got 65mpg on the way home from the gym. It could have been higher but I had to stop at a traffic light. The previous best of 63mpg mentioned above was without stopping at any lights. I will see what I can do on my drive to/from work tomorrow.

Awesome! This makes me happy, echoing Wayne. :)

I'd love to see a write-up on this technique in a gasoline-engine vehicle, such as mine. I currently do not use P&G for two reasons: 1) crazy drivers, 2) lack of knowledge about how to perform the technique successfully in a combustion engine.

I drove the Fusion 1.9miles to the gym at about 40mph.

Ummm???