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Yep, you read correctly.

This mode is something I had a chance of trying on my last trip to HybridFest 2008 in Madison and may very well represent a big plus for those who do a lot of highway style driving. Coincidentally, Wayne (xcel) had a 2008 HCH-II on his hands during that same week and he was able to validate the evocation details and the results with pretty much the same conclusions. You'll find Wayne's impressions and conclusions regarding this mode on his " 2008 HCH-II for a week review Blog (http://www.cleanmpg.com/forums/showthread.php?t=13754)" thread.

So, in addition to us now having a super-highway mode for the Prius II, we are now faced with a similar mode for the HCH-II and depending on your diligence you may be able to coax anywhere from 70 MPG to 90 MPG (2.6-3.3 L/100km). Please let us know if you manage to get better and for how long you can sustain it ;).


And now, to formally introduce this mode ...


SAHM (Super Atkinson Highway Mode)
(you should have a Scangauge not only to evoke the mode successfully but also to keep it on for as long as possible ;) )

How to evoke this mode : Set the ScanGauge to display the following gauges:IGN - Keep IGN between 30 and 36
LOD - Monitor LOD values between 40-60
MPG or LHK - optional
Mode's operational objectives: Vehicle speed:50-65 MPH (80-105 KM/H)
Procedure:
To get it into the IGN 30, one must reach a steady target speed (ie. 55-62MPH) and then ease into the 50-55 MPG (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=20) range (4.3-4.6 L/100km).

NOTE:
SoC must be at a good 7 bars in order for this mode to become available. The presence of 1 bar or hidden regen will deny you this mode. Drive for a short while and it will quickly become available.
Drive steadily for several minutes after a stop in order to get this mode back.
The platform must be sufficiently warmed up, preferably at stage 3 or better.
When the FE (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=21) stabilizes simply lift the foot off the accelerator ever so slightly and then gently re-apply. This will have the effect of bumping the IGN up a notch into the mid 20's. If you notice the FE (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=21) you'll see yourself getting bumped into the 60's (3.6-4 L/100km)or so.
At this point, lift the foot off the accelerator pedal again in the same way and re-apply. This last step will bump the IGN even higher into the 30-36 range. Along with that, the FE (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=21) also climbs to the 70-90 MPG (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=20) range (2.6-3.3 L/100km). Now the real test begins of keeping it in this range.Remarks: To keep it in the second IGN bump, I monitor the LOD values since if they grow too high beyond, say 60, the IGN begins to drop... and if it drops too far then you literally fall off the SAHM mode.

Conversely, if you lighten your foot too much, the IGN climbs beyond 34 and the chances of getting kicked out of the mode also increase.
So the trick, (for me at least) is to monitor the iFCD (http://www.cleanmpg.com/forums/glossary.php?do=viewglossary&term=51), IGN and LOD and simply ignore the speeds. This should be pretty natural to many of us as this is basically the DWL technique.

Ignoring the speeds actually worked very well for me as I could keep this mode on even as I climbed the smaller hills. Anything moderately steep or steeper and the LOD simply grabs you and pulls you off this mode. I suspect the grade logic control has a hand here too.
Enjoy and and let us know how it works for you.

Cheers;

MSantos

New update:

I just got some feedback (Thanks Paul) concerning the SAHM mode that finally confirms some other observations I had noted but was not sure of a couple of weeks ago.

Apparently, there is one other important determinant that stands in the way of not only evoking this mode but also keeping it for extended periods of time: The SoC.

In the simplest of terms, the SoC must be parked at 7 bars before this mode becomes lock-able... and it is not just any 7 bars but an adequate 7 bar SoC! This can be achieved by driving at a steady speed for a while and slowly the SoC will rest at 7 bars without much trouble. Once it plateaus at this level then the mode is easier to lock in on single IGN bump.
Obviously, I was not sure about this on my last highway trip because I kept a steady SoC for the entire 731 miles of the trip. But I did notice that every time I emerged from a pit stop, locking the SAHM mode in was difficult at least until a few minutes later.

I am going to be taking the family on a 4 hour camping trip to Hecla Island next week and I intend to double check on this while having the HDS station plugged in for the duration of the trip. Unfortunately, the Scangauge cannot co-exist while the tablet is on the ODB-II port, but I should be able to not only lock the mode in but also watch the SoC from a numerical perspective which is a better confirmation of the SoC's role in this mode.


Cheers;

MSantos

Have you noticed any change with the ice tempretures climbing. Could this be hard on the cat. conveters and the valve system? ::(

Hi Manuel:

___The 08 HCH-II I had for a week allowed SAHM in a lot more regions than what your 06 and 07 must allow? I could enter into SAHM at basically any speed above approximately 35 mph and could hold while DWL. I could also enter it at any SoC from 4-bars on up. During one forced charging events from 4 to 6 bars, I was even able to hold it from the fifth to sixth bar! I was running 60 + in the Bridgestone Insignia’s which I think might help enter and hold SAHM easier them most even thought the car had less than 5,000 miles on the odometer.

___Below 35 mph, her RPM was in the 1,100 RPM range and I would see IG14/TPS 14 where she would hold that magic 100 mpg + range while just barely touching the throttle in the most gentle of DWL scenarios. I do not know if that helps?

___Next item. All my “in the driver seat pics” were completely unreadable. I will curse this Kodak until the day I die :mad: The next time you are out, could you have your wife take a snap of your SG-II while displaying English units from the back seat for the HCH-II review I have to start putting together? If not, I will try and get a test drive of an HCH-II from my local Honda dealer with my son in the back snapping pics of the ScanGauge showing SAHM.

___Harold, just my thoughts but there are no mis-fire events during SAHM so the CAT is not being stressed. In fact, I can almost bet it is as happy as it could ever be being fully lit and the exhaust gas flow is as small as can possibly be achieved before valve closure in EV-Glide :)

___Pack temps would not be involved here either because you are not drawing or filling 98% of te time you are “in the SAHM zone “ :D

___Good Luck

___Wayne

Hi Harold;

Not reason to worry. Under this mode, the vehicle is not only operating in a safe range of temperature and emissions wise but also on its most optimal FE range. As previously confirmed, this mode is not an anomaly but rather an implicit feature/behavior owed to the design characteristics of the power-plant.



Hi Wayne:

___The 08 HCH-II I had for a week allowed SAHM in a lot more regions than what your 06 and 07 must allow? I could enter into SAHM at basically any speed above approximately 35 mph and could hold while DWL. I could also enter it at any SoC from 4-bars on up. During one forced charging events from 4 to 6 bars, I was even able to hold it from the fifth to sixth bar! I was running 60 + in the Bridgestone Insignia’s which I think might help enter and hold SAHM easier them most even thought the car had less than 5,000 miles on the odometer.

___Below 35 mph, her RPM was in the 1,100 RPM range and I would see IG14/TPS 14 where she would hold that magic 100 mpg + range while just barely touching the throttle in the most gentle of DWL scenarios. I do not know if that helps?


Good point, but I believe that is yet another mode altogether as the operational profile is somewhat different (as indicated by the IGN and other readings), but yet with similar iFE results. I personally confirm that engaging this low speed mode with a less than 7 bar SoC is definitely possible (as long as a forced regen routine is not under-way).

The other odd thing I did not mention is that the "higher speed mode" seems to have (and some of us managed to somewhat confirm this), is that the RPM is not always a reliable indicator of mode's presence since it may easily vary from 1500 RPM to almost 2000 RPM without changing the iFE much.

...The next time you are out, could you have your wife take a snap of your SG-II while displaying English units from the back seat for the HCH-II review I have to start putting together?

Yes, I will certainly do that. it should be much easier now that I actually have someone to hold the camera for me. :)


Cheers;

MSantos

Hi Manuel:

___Thank you!

___The IG14/TPS14 at an RPM of 1,100 is what I believe both Tarabell, RHwinger and Bear15 see quite a bit on their own daily grinds. I was looking at the pics of Tarabell’s FCD(s) and tach (I have the larger originals from when we first setup that article) and saw the same thing in the review HCH-II at the lower speeds. It is definitely not SAHM given the IGN, TPS and speeds but it sure is nice to see it once the lights and traffic has been cleared ;)

___Good Luck

___Wayne

___The IG14/TPS14 at an RPM of 1,100 is what I believe both Tarabell, RHwinger and Bear15 see quite a bit on their own daily grinds...

That's the one.

That particular low-speed-steady-state high FE mode is quite easy to evoke once the ICE warms up past stage 3. All you have to do is stabilize your foot after reaching the target speed and the PCM+ECU will do the rest. Around these parts we call it the "mid-3s" because when you have the iFCD displaying in metric the iFCD plants itself midway between the 0 and 6 L/100km into the 2.5 to 3.7 l/100km (65-94 MPG) FE zone. Keeping it there is also easy since all it requires is moderate steadiness on the foot .
I am also guilty of squeezing that low speed mode for all its got on a regular basis during the summer months. During the winter months its another story as the ICE+PCM barely make it past stage 2. :(


Cheers;

Manuel

So when are the Highway Tours going to begin?

12.3 gal tank, + a 0.7 gal over stuff, + 77 mpg SAHM = 1000 mile SAHM range.

Interesting!

11011011

Highway Tours? (sorry I feel like a decapitated chicken as I never heard of that before):D


You mean... some kind of an FE/Distance challenge of some sort just to teach the pre-historic automotive press a thing or two about hybrids on the highway? :) Oh man, would I love that !!!

Cheers;

Hi Dan:

___As you noted, this is one of the areas where an HCH-II can walk over a Prius-II. And it can be held up to 60 mph albeit at an ever lowering mpg as speeds climb. In any kind of stop and crawl or impediment laydened segment, I would sometimes curse the efficient girl because she wasn’t a Prius :(

___Manuel, why don’t you work on your Honda connections up North as the Canadian press always has some kind of cross the country challenge going on. Who better to take an HCH-II across the Continent on less than 3 tanks of fuel in the summer :D

___Good Luck

___Wayne

Thank you ,to you manuel and exel. H:)

...
___Manuel, why don’t you work on your Honda connections up North as the Canadian press always has some kind of cross the country challenge going on. Who better to take an HCH-II across the Continent on less than 3 tanks of fuel in the summer :D



Wayne,

That would be a memorable challenge for sure... and I would love to do it just to see the look on my wife's face (she would think I finally went crazy) :D

Lets see:
From Halifax to Vancouver with at least two drivers and one car, and... assuming that we do get avg 77 MPG we would need at least 4 fillups for these 12.4 Gallon tanks ($5.5 USD/Gallon, this year's Canadian gas pricing):

SUMMARY
Driving distance: 3750.0 miles
Trip duration: 5 days, 5 hours, 34 minutes
Driving time: 71 hours, 34 minutes
Fuel Cost: $278.56


If we got a 70 MPG avg, then 5 fillups:

SUMMARY
Driving distance: 3750.0 miles
Trip duration: 5 days, 5 hours, 34 minutes
Driving time: 71 hours, 34 minutes
Fuel Cost: $303.37

If we got a 65 MPG avg, then at least 5 fillups:

SUMMARY
Driving distance: 3750.0 miles
Trip duration: 5 days, 5 hours, 34 minutes
Driving time: 71 hours, 34 minutes
Fuel Cost: $324.37


Thinking cap on:

A partnership with the automotive press (yuk, they do this regularly) would definitely not work as they are all chronic lead foots. I think many of them would rather pick a voluntary lobotomy instead of driving for so many days with a focus on FE. :(

Getting press coverage from the general media would not be a problem as that would be a simple matter of making half a dozen phone calls. Then, we would just have Honda Canada wire a short press release a day before the event to nail the remaining press channels.

Anybody want to ride along in a challenge like this ? :D :D

Cheers;

MSantos

Hi Manuel:

___Let us say we can filler er up with 13.2 gallons and I know of at least one volunteer... And possibly 10 more ;)

___Good Luck

___Wayne

The Rockies may throw a wrench into the ointment!!! But it is fun dreaming? ;)H

Hi Harold;

It sure throws a big wrench into it, all right. I figure that in total we have roughly 611 miles worth of agonizing SoC/RPM pain and suffering ;)

Cheers;

MSantos

To me,, this sounds like what I do daily. Pulse and bleed cycle. Even in the Mazda I can see several miles tick off at 72 mpg until load becomes unmanageble. Then its all gone.

I don't have the SG in the Mazda. but do use the hacked DIS. Its slow. but does work. The Civic use to post up numbers in the high 80s to low 90 mpg range if you got it in a super hwy mode.

Wayne,,,, how does the Accord respond to this type of driving? I will see what our Accord does next week when I get to drive it.

12.3 gal tank, + a 0.7 gal over stuff, + 77 mpg SAHM = 1000 mile SAHM range.

Based upon my experience from the 5 times I've topped off my HCHII, you can get about 1.9 extra gallons in by topping off. The most gallons I put in was 14.035. I assume it was pretty close, but I didn't run it dry.

Hi Jeff:

___The SAHM is not a DWL/DWB bleed off and pulse but a DWL/DWB steady state cruise with the iFCD in the 70 to 90 range up to at least 60 mph. I did not go much over 63 mph using it the entire time I had the HCH-II but you keep losing 5 mpg pips the faster you go ;) The Accord will hold 52 mpg at 52 mph but the HCH-II is worth a lot more.

___Going back to my first 80 + degree segment to downtown Chicago and back, she allowed 82.2 per the FCD which is low by 1.5 to 3 mpg vs. actual. This was pre-rush so the roads were still relatively wide open and this is where she shines. 45 – 60 mph, IGN 29 - 36 and a TPS of 17 or so. Keeping LOD under 50 is a must as well. I keep forgetting about that as Manuel has described throughout the forum more than a few times.

___Good Luck

___Wayne

Hum, and I thought i didn't need a scangauge for my HCHII since it had a tach already...

$170 only to achieve SAHM...

I achieved the super highway mode on my way home this morning WITHOUT the Scangauge. I could keep it in o.k. at 40 to 45 mph, but around 55 mph, I couldn't keep it in. Using the Scangauge though had taught me "the feel". I'll be traveling with the Scangauge again tonight.
It won't cost you $170 though. You can get in on the group buy (http://www.cleanmpg.com/forums/showthread.php?t=14480) for $20 less.

Does this mode exist in a 2000 Insight with MT ?

Hi Armadaman:

___Your Insight 5-speed has lean-burn and with the OEM iFCD, you will see the jump in FE at lower speed highway cruise. There may be an IGN component but with the 150 mpg bar graph, it is relatively easy to hold and maintain your fuel miser in that fuel efficient region without much work other than a very light amount of footwork :)

___Anyone with an Insight 5-speed want to watch IGN while entering and exiting Lean-burn for us please?

___Good Luck

___Wayne

Wayne,
Thanks again for your help.I can tell I have alot to learn and will learn with all the knowledge
of the members of this site.

Hi Armadaman:

___I hope you will be teaching us in the very near future as you have two of the best fuel savers on the planet sitting in your drive. I know at least a thousand of us would like to be in your shoes and thank you for owning such fine pieces of fuel saving propulsion technology! If I could only be so smart to have done the same…

___Good Luck

___Wayne

I'm not sure about the scan gauge, Owlmaster. That is a big jump in FE, so we should see the differance? I,m going to try anyway, before I take the plung! H:D

I'm not sure about the scan gauge, Owlmaster. That is a big jump in FE, so we should see the differance? I,m going to try anyway, before I take the plung! H:D

Let me know how it goes!...I don't drive much these days since I bike commute to work. I haven't even used 1/4 of a tank since I moved here 5 weeks ago :P

70+mpg is extremely alluring though....If you think it's worth the plunge I'll take it too :)

I am going on a trip on the 11th Aug. too Saskatoon[flat lands]. I will give it the old one-two out there. I will let you know how I make out. H

Wayne, you can redeem yourself by getting on a waiting list for a Prius-III or Honda Global Hybrid now...

Hi Ben:

___Someday... when I have some distance to drive. The Wife, definitely ;)

___Good Luck

___Wayne

Ok, I had a Physical Readiness test today so I drove instead of biking. I usually get about 52-56 mpg on this 8 miles commute. It's a somewhat decent amount of traffic down a 6 lane road with lots of lights, speed limit 45mph. Today I decided to try to do either "SAHM" or the "mid3s"? Uusally I try to pulse and glide the whole way...Anyways, I kept my speed about 35-45 mph, and ended up with 62.7 mpg going there, 62.8 coming back! I thought pulse and glide was THE way to go, but this looks a lot better! (or I suck at P&G, lol)

Again, I didn't know what I was achieving for sure, but it worked :P I won't be driving again though for a while, back to the bike :D

That is a big bump in FE! Could you notice a change in FE when SAHM kicked in? Must be much easier driving with SAHM than Pulse and Glide as well. H

Hi Owlmaster:

___Because of the HCH-II’s poor acceleration performance you may have to bury the SoC and jump on the pedal to get P&G to work properly. IN the review HCH-II, I did not have the time to find out. I have driven Terry Honaker’s HCH-II to > 100mpg but with the review vehicle, I was only using a 4-bar SoC and holding. Less assist affinity there but still gentle on the pedal. The results were less by almost 20% but the feel of a gentle more gentle pulse felt much better for the vehicle’s longevity. Like I am supposed to care about a review vehicle but I hate it when these press vehicles are abused by the likes of C&D, R&T types who could give a $&*! About anything but their publications.

http://www.cleanmpg.com/photos/data/504/103_0_mpg_19_5_miles.jpg
Std. high load P&G after burying the SoC to 3-bars and forced charge on each pulse.

http://www.cleanmpg.com/photos/data/523/85_2_mpg_over_19_9_miles_of_Low_and_Mid-speed_P_G.jpg
Gentle P&G while holding a 4-bar SoC.

___All that being said, I saw a segment with the aFCD at 82.2 while traveling 85 to 90% slower speed Interstate into a Chicago neighborhood pre-rush using SAHM on my very first drive.

___Temps are even more of a consideration with the HCH-II and SAHM. In the 60’s and low 70’s, SAHM will allow 75 +. In the high 70’s and low 80’s, 80 + driving under the same constraints in my experience.

___Good Luck

___Wayne

SAHM is a winner! I was able to use a Scangauge for 1 day when I started back to work this week. I've got to quit loaning them out! I had the rear control arms changed yesterday and 4-wheel alignment (warranty) and it seemed to come in and stay at a higher speed much easier. I was flying blind though without the Scangauge.

This is very interesting...Looks like Wayne can really P&G :P. I feel embarrassed now hehe. Before I would just call this continuous gassing "feathering" the gas pedal as Tarabell called it I think. The key from what I see is you get up to a speed, let off on the gas a little, then easily reapply a little. When you let your foot off the FE bars go to max. When you reapply they go down a little. If you don't reapply enough, your bars stay really high but you slow down too much. If you apply too much all your FE bars drop like a rock. You have to be pretty easy with it or you slow down to much or you kick it back to normal driving. I think this is right? (If I am wrong let me know :) )

I have done a couple trips this summer P&Ging that I have gotten 70 mpg on, about 15-20 miles or so, but 103 is crazy! For heavier traffic it looks like SAHM is the way to go, now that I understand it better. I may have to jump on getting a Scangauge, it looks like a worthwhile investment for a HCHII hypermiler now. Now that I have a real job that makes money I can splurge a little :D

Well, while my vacation continues, my short trip with the family to Hecla island is now over. So, I just managed to get the pictures out of the camera.

Now, our trip to Hecla was devoid of any significant hills but the car was really loaded. The tires were pressed at 50 psi and temps on each tire varied from 28C and 32C depending on which side was being hit by the sun. The fuel tank was full on departure and the ambient temps were very good too as 24C-27C and the winds were very light.

Also, it helped a lot that my wife was riding the back seat with my daughter ready to take the shots as needed.

Now, the SAHM mode was very hard to sustain while the SoC was less than ideal. This is because the LOD would climb due to this constant micro regen. Anyway, the following is a picture of my short lived attempts to keep the mode on (I was averaging a measly 67 MPG). :(

http://www.cleanmpg.com/photos/data/500/medium/To_hecla_Bad_SOC.JPG

Sometime later, more like towards the end of the trip to our destination I decided it was time to take another snapshot (after my wife woke from her short nap). So she grabbed this one in the midst of a good run (at this point the SG was reading 100-120 MPG as per SG-II and my wife got the high point).

http://www.cleanmpg.com/photos/data/500/medium/to_hecla_good_soc_1024x768.jpg


Now, a short diversion from the technicalities of Fuel Efficient driving::p

I just wanted to prove to myself that it is VERY possible to load up an HCH-2 with 2.5 people, a 7 person tent, two full size inflatable beds, grill and stove, electric cooler, chairs, 2 sun umbrellas, and food for 4 days and 3 nights. Just don't ask me how I did it. By the way, there's literally no space left in the trunk and one of the seats (the front passenger seat) was fully load with cargo too. Yes, that is a CleanMPG window sticker. Thanks Mike, I took your advice concerning its placement. :D
http://www.cleanmpg.com/photos/data/500/medium/How_to_Pack_an_HCH2_1024x768.jpg

Anyway, back to the goods on the SAHM...

The following picture is something that I took by myself during our return from our camping trip. I took many but this is the only one that came up the least blurry. This time I did not want to bug my wife as she was playing scrabble with my daughter and man was that ever a long game which left me to take the shots on my own (I was getting 98+ MPG as per SG-II in this stretch). :rolleyes:
http://www.cleanmpg.com/photos/data/500/medium/from_hecla_goodsoc_1024x769

The following snapshots were captured on the driveway right after our return. The next shot is that of the aFCD showing the B trip meter which was reset just before our departure.
http://www.cleanmpg.com/photos/data/500/medium/from_hecla_afcdsummary_1024x768.jpg

The next image is that of the ScanGauge summary for the day upon our return from our trip. This included a bit of slow driving inside the provincial park due to some road works and reduced speeds. There was also another detour on highway 8 that forced us to take up a slower but more traffic laden alternate route. All in all it was only a 35-45 minute penalty.
http://www.cleanmpg.com/photos/data/500/medium/from_hecla_sgsummary_1024x768.jpg


Conclusions:Well, this SAHM is very finicky especially regarding the more detrimental variables. This includes head winds and the weight of the vehicle both of which I managed to experience in the recent attempts. On my way there, we were very heavy and it was VERY easy to drop off the mode. This required huge amounts of concentration and a very steady foot... and by the way, if you just started reading this, then I will remind you that cruise control does not apply here. ;)

When I first tried this mode on my way to Hybridfest 08 I arrived to Madison with a cramp on my right ankle like I never had in my life before... and I did that type of driving for the better part of the 14 hour trip.
This time on a much shorter trip I arrived with a sore ankle which dissipated quite quickly but still it is something I would consider before doing it regularly.

On the way back from Hecla the HCH-2 was much lighter and It was definitely easier to keep the mode on without bleeding the speed.
The MPG results:The odd stuff here is that I had two scangauges both working on slow rate mode and one of them was displaying the iMPG while the other was displaying the iLHK and the values did not agree. The MPG values were outrageously high when compared to the iLHK. Either that or the iLHK were very understated.
In the end the SG-II average MPG was much higher than the the HCH-2 instrumented aFCD and if my past experience is any indicator, the actual fuel economy is somewhere between the SG-II aFCD and the HCH-II aFCD. :rolleyes:

There are a few other oddities that I will have to think about before posting any further. But for now these are the raw results.
Cheers;

MSantos

Great pics and awesome mileage! :)

Hi Manuel:

___I cannot wait to get into an HCH-II again as your road pics made it a sight to see! Great and I mean great job as that is the highest family vacation FE possibly seen here in the US and possibly the planet!@

___Good Luck

___Wayne

Hi Wayne and Sean;

Thanks, but I don't really have good news especially since I checked the actual achievement at the pump. :(

As I expected both scangauges were way off the real mark. In fact, the car's own aFCD was off too and by the widest margin I had ever seen.

I went to the pump this morning and filled the tank up to the first click (as I always do at the same gas station). In total, I consumed 14.2 Liters (3.75 gallons US) to cover a distance of 423Km (256.62 Miles). This places the actual fuel economy performance at 3.4 l/100km or 69.2 MPG US.

As usual the instrumented mileage performance is to be taken with a BIG grain of salt and in this case make that a truck load of it !!!
And here's the worse part: The scangauges were not in agreement with each other either !!!

Here are the details (I did not reset the tanks, so these are just the details for the day trip):

Left Scangauge II (3.0X)Trip distance= 127 miles (204 km)
Trip fuel used= 1.58 gallons (5.98 Liters)
Trip duration= 3.6 hours
Trip MPG=80.3 (2.94 lhk)
Right Scangauge II (3.15 -W XGauge) Trip distance= 192 km (119.3 miles)
Trip fuel used= 5.75 Liters (1.52 gallons)
Trip duration= 3.0 hours
Trip MPG= 2.9 LHK (81.1 MPG US)
As I mentioned before, what is worse is that while on route the iMPG display on the left gauge did not agree with the iLHK on the right gauge. In fact, the discrepancy appeared so large that I wondered if there was an interaction issue between the two that prevented one of them from computing accurately... or it was just the fact that both scangauges had differing firmware revisions. :confused:

But still, when operating in this SAHM mode the scanguage MPG readings are too optimistic and unrealistic. Also surprising is the HCH-II's aFCD as it too, overestimated the MPG performance when usually it is the other way around.
There is no question that this mode creates some very unique operational scenarios where the instrumented display of the fuel used is just fraught with a lot of calculated error... so much so that it becomes nothing but a weak estimate at best and really nothing to boast about.

A usual, nothing beats a hand calculated assessment of actual FE.

Cheers;

MSantos

Hi Manuel:

___Was that top off to top off? In the HCH-II review vehicle, she had about 75 - 80% highway with most sitting in “SAHM” and the top off to top off actual yielded 73.2 mpgUS vs. the 71.5 mpgUS displayed per the OEM aFCD. I saw the same large ScanGauge-II error with 0% offset and a reset ScanGauge-II which read 83.4 mpg over 503 miles for the week long drive.

___At times, the ScanGauge-II's iMPG would read an Insight like 100 – 115 mpgUS at 40 - 55 mph in a lot of areas while under “SAHM” when I know it would not be possible to receive Insight like fuel economy from the somewhat heavy 4-door sedan. Maybe the iCDTi but not the DSI which proved to be the case with the top off to top off fill yielding 73.2 over 503 miles.

___While you were out on vacation, we missed you around here too :D

___Good Luck

___Wayne

Hi Wayne;

Yes, that was top-off to top-off, all done at the same pump (Shell).

I am not terribly disappointed at the actual mileage I got at all - well kind of. Now that I think about it, I missed the 70MPG mark by a small bit and even though the weather conditions were very good and the roads were almost ideal, the car was still very loaded at least on the first trip. I guess I failed to bring up the mileage high enough on the return trip to bring it over the 70 MPG mark. But I did notice that my return trip yielded better results perhaps on the account of the car being somewhat lighter. Wind was negligible and the AC was running strategically mostly in electric so it too should not have been a hindrance.

In retrospect, this "mode" will really work far better for people commuting on the highway over a good enough distance... on a properly setup car with not too much weight on it. I figure that under these scenarios getting 80+ runs on a regular basis should be doable if the diligence and conditions are there.

I guess the key for me is also to not get overly excited about the SG-II mileage being reported, either instant or averaged but instead use it as a relative measurement of potential success. As always, the measurement of actual fuel used while still not full proof is still king in my books. :)

I'm still on vacation but since I am closer to urban centers, being online is easier than being at a remote location where mobile communications are non-existent. ;)


Cheers;

MSantos

Manuel,

Awesome thread!!! Thanks for sharing this very important technique with us. We hope you are enjoying your vacation. I know for us, part of the fun on a vacation trip is what you illustrated-- going after high mpg!!

I read this thread with great interest, as it appears that this mode is not unique to hybrids. I accidentally "discovered" 55-65 MPG at ~43 IGN the other day. Like you say, the mode is attained by gently backing off the gas from about 60 mph. Unfortunately, my terrain is too variable to stay in the SAHM for long, so extensive testing is difficult (hint: anyone with a car like mine want to test this on flat terrain?).

I have also seen the 75+ mpg low-speed sweet spot Wayne mentioned at ~23 (IIRC) IGN. Again, due to the terrain bugbear, I'll need quite a bit more time for testing; there is not much low-speed level roadway in my commute.

Way to go! :flag:
-jon

EDIT: BTW, thanks to 70_West for bringing this to my attention. :)

Is the SAHM a Pulse and Glide technique? Without looking at the scangauge, is the car essentially slowing down, and when exactly do you speed back up?

I will be driving about 900 miles this labor day weekend so I have lots of time to try techniques.

I would like to go an average of 60MPH the whole trip, so in this case, would I start off at like 65MPH and slowly go down to like 55MPH to get the mileage. After this, how quickly should I get back up to 65MPH? I'm guessing I should avoid assist to get back to 65

Thanks!

Hi Hunter

It is definitely not a pulse and glide variant. It is a stable, steady-state pattern that leverages the gas-engine's low cam mode features, and the PCM's control of the CVT.

In reality you'll want to use this on a highway where a steady state of speed is possible. You can retain the mode when climbing small hills and as long as the loss in speed is bearable to you. You can also use it mild descents as long as the upper speed is safe as well. I've had it in mild descents sometimes reaching 80+ MPH (kind of scary if you are not accustomed to these speeds).

While you can do it without a scangauge, the SG is instrumental for locking it in with your accelerator pedal and keeping it on for as long as possible. 75+ MPG (@ 55-62 MPH) is quite achievable - even with a somewhat loaded car. ;)

Cheers;

MSantos

Thanks for the quick reply Msantos - I am driving from Cleveland to Chicago (rnd trip) which is really flat as there are no mountains or even large hills.

I -do- have a scangauge and will give it a shot. I just wanted a perspective of what the vehicle itself was doing speed-wise and you answered that.

SAHM the heck out of it hunter! :)