Pulse and Glide plus Warp Stealth in the Prius II for maximum FE …

Wayne Gerdes - 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


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​

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


Example of a 16 mpg Pulse rate.​

Example of a 23 mpg Pulse rate.​

Example of a 32 mpg Pulse rate.​

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


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


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


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


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


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. 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.”.

Warp Stealth


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


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

 

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

 

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

___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 Tochatihu:

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

___Good Luck

___Wayne

 

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 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

 

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