___I did not believe this was possible either until a daring Prius II pilot named Krousdb showed me the light about 3 months ago. When you put it all together, you begin to understand why the Prius II receives such a high EPA in the FTP75 (City) test cycle. Its ICE is only running ~ 48% of the time. The ICE is not allowing you 60 mpg but only an average of ~ 28.8 mpg of the EPA test cycles total distance and the rest is a regen based coast down/EV mode acceleration or speed maintenance. P&G just takes it to the next level w/out any
regen or assist. It is only to be used where appropriate however.
___I remember when I first spoke to Rick Reese about joining us for the “Marathon – Attempt” maybe 2 + months ago and he said he did not think a Prius II was capable of 100 + mpg sustained. I showed him some real world results and bingo … Case in point; he had the highest average
of all of us during the weekends extreme hypermiling drive!
___The balance and theory … If you can achieve a steady or overall, 33 mpg acceleration rate in any automobile over let us say 2.5 blocks, you only need to achieve a FAS or Glide for 5 blocks while ending at slightly above or equal to your original/initial Pulse speed to achieve 100 mpg. The kicker is that not only can you average > 33 mpg over a given distance during your pulse, you can usually glide > 2X’s the Pulse distance in the Prius II and the HCH. It doesn’t really matter if you have a 33 mpg on average Pulse, 20 mpg on average Pulse, or a 45 mpg on average Pulse, you just have to get the ICE “off” time over the correct multiple of the acceleration distance to achieve what some had thought impossible just a few months ago. Let us use a 20 mpg pulse as an example this time. With that acceleration rate, you may have only accelerated for 1.5 blocks. On the Glide, you need to achieve 5X’s the pulse distance or 6.0 blocks of coast and you have achieved 100 mpg over the 7.5 blocks. You can do the math with any number of acceleration rates and ranges but the trick is to find an optimal acceleration rate, optimal speed range to perform the technique in, and to maintain a SoC at some level without using Assist or Regen to maximum the techniques potential. If you cannot maintain the SoC, all bets are off and the technique may indeed fall apart
___Given the way the Prius II was designed, you can perform everything with a very self-controlled application of the accelerator including its pack SoC algorithm so that it will only allow a charge from the ICE to the pack via the MGSets at a particular acceleration rate. With the HCH and Insight, there are quite a few other gyrations involved as you know but the results speak for themselves. In the case of the HCH anyway. The above is the how and why the technique works in both the Prius and the HCH. Because of the Insight’s much lighter weight, I can see a full blown P&G achieving 125 + sustained without much thought but I do not have my Insight anymore to see what is and isn’t possible from one. The question I am really interested in however is how the SoC will behave in the 5 speed after multiple P&G cycles? I would not mind seeing the SoC of the Insight drop to 3 or 4 bars as long as it stays there with a small amount of Forced Charge during any Pulse throughout any number of P&G cycles afterwards.
___Another item … This should only be perfected on an empty road course before bringing the technique into your daily - real world - commuting realm. There are too many distractions at first and the technique has to become second nature or it is not worth performing! In terms of pack damage, it is the wild assist and regen current flows into and out of the pack that cause the damage in an Insight, HCH, or Prius II’s pack imho. That question is for another thread and for people a lot smarter then I to come up with the how’s and why’s. My own thoughts are to “Never use the pack and you will never have any problem” …
___Please look back at the Tbaleno’s HCH we P&G tested 2 days ago for the proof of concept or where the wheels meet the road. The last 2 runs averaged 100.8 mpg and we had still not fully optimized the technique plus we had two in the car with a ton of his stereo gear, spare tire, and other stuff in the trunk! We were running slightly < 50 #’s in his Bridgestone’s which certainly did not help matters either … Steady state cruise in the HCH is only worth a maximum of ~ 80 mpg from what I saw in the FCD display. With your normal traffic accel/decel losses, her maximum is back down into the 75 mpg range and that is ~ what I received out of her with 10% city and 90% highway operation over 130 + miles. Add a few FAS’ and you can get her back up to ~ 80 mpg but that is about it. You cannot achieve 100 mpg steady state driving a non-wind aided flat road in the HCH as it is impossible no matter what your speed. You can however achieve > 100 mpg sustained in the HCH under P&G because of the above and as we saw in our test runs.
___I hope that helped?
___Finally, I can see Mike D’s gears in his head whirring around and hopefully he can come up with a FAS via Mima without all the gyrations because the way to a higher FE future is with much lower ICE run times over a given distance traveled if we like it or not. Honda hasn’t figured this out yet but they will soon enough.
___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.