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About a month ago I came across an article about the Prius II marathon last August and thought no that can't be right 110 mpg in a Prius! Upon further investigation I have realized that at speeds under 40 MPH this is possible which is not news to some of you because you were there driving the Prius. Your amazing feat inspired me to try to put some FE techniques into practice.
My LMPG for my 2004 Prius II is only 51, but over my last 10 tanks my avg mpg has been 58, and over the three tanks since using P&G as much as possible my average mpg has been 65. Also I finally broke the 600 mile tank barrier (at 664, previous best was 580) and got my first tank over 70 MPG! This is nothing compared to 110 or some of Dan's other tanks last summer in the 80s before the marathon.
I would love to hone my FE skills (or become skillful) by getting some tips from the masters. I read through the entire Marathon live update thread at Green hybrid to try to get a feel for any improvements in technique that were learned over the course of the marathon. Dan had mentioned that people should submit questions that could be answered after the fantastic 4 (or 5) got some much needed rest. I am not sure if this ever happened or if any synopsis of what was learned was ever published. It seems that much was probably learned by experience and maybe discussion among 5 skillful drivers about how to get the best FE out of a Prius II and maybe other vehicles as well.
As far as I can tell 3 of 5 of the marathon team are members here and the other two may be but don't post as much or may look in from time to time. Did Wayne do something dramatically different to post the 120 MPG shift, and was the seemingly slower avg speed intentional or was there a stop in the middle for some reason which makes the seemingly slower speed an artifact? Can anyone explain what was meant by Rick's MIMA like technique? When Dan was using his DWL plus P&G technique what instantaneous FE was he aiming for on his pulse and did he decide the deadband during the pulse was of little advantage? What tire pressure do you elite hypermilers use? I have gone from 40 up to 50 and I know during the marathon 60 was used, does anyone run at 60 PSI at highway speeds? I like hobbits page on warp stealth, the information is great and I have been trying to use this as well. Hobbit have you ever tried testing warp stealth vs cruise control and was there much difference in FE, it seems to me at an average speed of 50 MPH there is a slight improvement in rolling hills, but I need to experiment a little more to see if I can quantify it.

Dennis

Welcome to CleanMPG!

Welcome to cleanmpg. As far as I know Rob Barlow doesn't come here. He doesn't go online much and his last visit to greenhybrid was about 2 months ago. Wayne and Dan are pretty active here so maybe they can start a thread with answers to your questions.

Hi Dennis:

___Welcome to CleanMPG and it is nice to see a new member asking the kinds of questions that you are …

___Since you have already read enough on P&G and more then likely all the acronyms in the CleanMPG glossary, you probably have a very good understanding as to the how’s and why’s you are achieving the excellent FE that you currently are. Your FE achievements parallel’s Carl H.’s (a friend of mine) who purchased an 05 and was achieving in the mid 40’s at first, learned P&G (I used his car for my local practice runs), jumped into the low to mid 60s’, held on to whatever he could through our Chicago winter temps and conditions, and has been honing his technique including finding alternate routes to punch out well over 70 mpg’s on his latest tank. His next goal is 80 mpg’s given 70 was a stretch goal and he nailed that by late May! With that, I will answer what I can as I remember it.

___With regards to the 120.x mpg segment, I was traveling slower then the rest, I had less traffic due to it being early Sunday morning, and the temps were absolutely optimal for maximum FE. I did stop after the second leg of three given I drove a night shift on Day 1 and first shift of day light on day 2. I was really tired and extremely excited at the same time but planned on ending my drive then. I mainly stopped because the SuperMID went above 50 Km/L for the first time and I wanted a pic. Unfortunately as I was gliding into the hotel parking lot w/ a touch of EV, the ICE came on due to a low SoC and dropped her back just under 50 Km/L while idling in the lot. A few pics were taken and RJ said have another go (he didn’t want to see Rick R. drive off with a SoC that low ;)) so fortunately off I went. That last 30-mile segment was a blow out given I finally came to realize some of the Prius II’s and the courses secret’s in perfect temperatures, perfect conditions, and with the least amount of traffic. A little EV to get over the humps, DWL up the steeper hills at even slower speeds, ICE-Off EV over the crests, and always staying below 41 mph by using the course itself to drop down to the proper speed as I crested so I would never enter regen on the back side in a glide through some of the steeper descents. I was limiting my Pulses no matter if it was uphill, flat, or downhill to maintain at least 50 Km/L during that last 30 mile segment and to maintain the 5 minute bars pegged at 99.9 mpg’s all the way across. All of this and I arrived back at the hotel to hand off to Rick with the SoC clearly in the Blue. I was just plain fortunate to be driving at that exact period in time is all.

___Can a Prius II be driven for 120 + mpg anywhere and at any time? Not a chance but on that day, with the minimal traffic, in those temperatures and conditions, and that course, she was worth even more if you can believe that!

___I want to add how important temperature and weather conditions were. During the first and second night shift, Dave Bassage received the worst of the elements. On Dave’s first run, it was raining for ~ ½ his drive and temps were in the low 60’s. Remember this was during the middle of the night so headlights were mandatory which is another FE killer when pushing to this level! I was on the Cel phone with Dave during his first run and described to the best of my abilities how to RR so as to reduce the water push and lift. During my run that first night, I drove through the same rain and temp conditions and was using the RR technique to the best of my ability as well. Dave had a second night shift slot which unfortunately for him, it was raining again for ~ ¼ of his drive. The temps were up a slight amount (mid 60’s IIRC) so that may have helped him a little? Because my second run at the course was in much nicer temps (69 - 75 degrees F), no rain, and day light hours (no headlights), I have to believe both temps and road conditions played a huge factor in the results. Dave would no doubt have achieved far higher FE then he did if he had the opportunity to run the same conditions. It just didn’t work out that way is all :(

___All of the above being said, what we found was that the Prius II is a FE animal in its element below 40 mph’s. It does not matter if you Pulse at a 50 mpg rate (I liked that a lot), a 20 mpg rate (I used this as well), or anything in-between, as long as your Prius II will go ICE-Off for each and every glide (some will not every time), the whole row of 5 minute bars can be nailed to the roof of the consumption screen at 99.9 mpg’s. Dan’s Prius II was really this flexible although I have driven some Prius II’s in not so similar conditions that were not.

___I use 55 – 60 #’s in the Accord’s Michelin MXV’s driving an ~ 80 - 90% highway commute (change in %’s depends on my shift and traffic conditions).

___Finally, thank you for introducing yourself! If you would not mind, could you create a similar thread with a more direct title (“FE based questions about the Prius II Marathon Attempt” or similar?) with your questions in the FE forum? Many more Prius II pilots will see it in the FE forum then in an introduction and I will C&P this reply into it for others to see as well. Dan should be along soon enough to answer what questions he can in regards to his particular segments.

___Good Luck and welcome again.

___Wayne

As always, Wayne is quite thorough in his replies. I don't have much to add other that to agree with Wayne that the acceleration rate did not seem to make a difference in FE. Maybe it is related to the Prius ability to place the ICE under optimal load whatever the situation. Hobbit's findings regarding the manifold vacuum was quite enlightening and also seems to point toward the same conclusion.

I would be happy to answer additional questions but I havent driven the Prius much lately. I'm sure between all of the Prius owners here, you will get satisfactory answers.

Welcome Dennis!

Thanks Wayne and Dan for the replies, I will repost my introduction under FE per Wayne's suggestion. I am thrilled to have been consulted by FE masters such as yourselves. I know Wayne doesn't drive a Prius regularly and now Dan's focus is getting unbelievable FE out of his del Sol, but you guys can teach a lot to those interested in better FE whether driving an F250 or an Insight.

Dennis

Eep, I didn't realize this thread had started until just now. Maybe
I should search for posts with "hobbit" in them every so often..
anyways, in vague answer to the warp-stealth vs CC question... the
differences obtainable for 55 mph and above seem to be very small
any way you cut it, and that's just because the prius seems to try
to stay in various efficient running modes by itself without much
driver intervention. But I do think that slight slowing on the
ups and warp-stealthing or trying to do low-RPM DWL equivalent
gains a bit more distance per droplet than letting the CC ram it
up to three grand up every rise. I haven't really gone out for
a well-structured comparison test -- such things tend to take
a good chunk of a day, and need unchanging conditions. Last time
I went up and back on my favorite stretch of I-95 for something
like this was testing the WAI hack, which I wrote up to the
Prius_technical_stuff yahoogroup and stuck into my little webpage
about it as an addendum.
.
So I'm still working on the general approach to higher-speed
mileage, and once I think I've got a better working body of
knowledge might *then* go out for the CC-vs-foot tests. But I
don't feel like I'm quite there yet. Maybe I need to go to
Hybridfest to get another couple thousand miles of lab time?
.
I *am* relatively confident that liberal warp-stealthing makes
large improvements in the 42 - 50 mph range, which helps quite
a bit on those secondary but still fast highways. You won't be
doing 80 mpg segments here, but I've gotten mixed 5-minute intervals
of abysmal and pegged with little discernible relation to the
terrain most of the time. Still, I managed 68.something on my
run to Tour de Sol doing a lot of that [and am still mildly
disappointed that I didn't do better]...
.
_H*

don't feel like I'm quite there yet. Maybe I need to go to
Hybridfest to get another couple thousand miles of lab time?.
_H*

Like I said earlier, you are going to Hybridfest, you just don't realize it yet.:D

Hobbit,

Thanks for getting back to me. I seem to see some improvement using warp stealth + DWL between 40 and 55 vs cruise control, although I have yet to try a more scientific test (comparing two loops with little change in conditions). Do you try to use deadband (no arrows to or from the battery) during the pulse or do you aim for a certain IFE? I used to try deadband, but this doesn't usually work well over 40 (an arrow usually is going to the battery while the ICE and Electric also drive the wheels), IFE is usually around 20-25 MPG. I changed strategy and simply use DWL at an IFE around 35 MPG (sometimes lower on a steep hill if I'm holding up traffic.) What do you find works well in that 40-55 MPH range? I may be repeating myself, but your warp stealth article was great. (I think your use of "dead band" may have been incorrect, the no arrows glide of P&G is not "dead band", it is during the pulse where arrows from ice and electric motor go to the wheels, but there are no arrows to or from the battery.)

Dennis