Hi Krousdb:

___That was the best HSD hypermileage tutorial I have ever had the opportunity to read to date and I want to personally thank you for it. I had only a foggy idea as to what was going on in the HSD at or around 42 miles per hour and you cleared a lot of my and I am sure others misconceptions up. I can only hope Jason makes your post and his thread a sticky. Actually, he could use the help in his Prius II

___I hope the following helps you in regards to IMA, hypermileage, and my experiences with it.

Tire Pressure’s: I ran pressures of 60 # for the record setters in the RE92’s and I would drop back to 52 - 56 #’s (normal leak off) for every day commuting.

Tire Break-in: Same thing with Insight’s RE92’s although I never had the opportunity to see 4 brand new RE92’s on my own at the same time. According to others that have replaced them with like for like, it is an ~ 3,000 mile penalty before they open up for maximum FE once again although no one has ever scientifically measured the actual FE delta from new on up that I have read?

Oil: Mobil1 0W-20 was its staple as it is in the rest of my automobiles. I horded a few cases so I have ~ 5 years worth for the Accord

___The following may be of some interest to you?

Kinematic Viscosities (ASTM D-445) of the respective manufacturer’s synthetic oils:

Mobil1 SAE 0W-20
cSt @ 40 degrees C = 43.0
cSt @ 100 degrees C = 8.4

Pennzoil SAE 0W-20
cSt @ 40 degrees C = 46.5
cSt @ 100 degrees C = 8.7

Mobil1 SAE 5W-20
cSt @ 40 degrees C = 48.3
cSt @ 100 degrees C = 8.8

Amsoil SAE 5W-20
cSt @ 40 degrees C = 49.6
cSt @ 100 degrees C = 9.0

Climate Control: Buttoned up tight at speeds > 30 miles per hour. Two windows open from a stop to ~ the same 30 miles per hour. Max Fan w A/C disengaged. Spray bottle and ice cooler on the 90 + degree days. This is where the Prius has me at a loss. Can you run max fan flow from the vents w/out A/C? I thought I remember reading that you could not?

Driving style:

Std. Hypermileage Mode: Accelerations held to just below or just into 4 bars of assist and backing off to remove them (IMA’s std. engagement and tough to keep out of in second gear) appeared to allow the highest FE over a given distance during accelerations. There was no forced or hidden charge hit later on to bring your overall down. This is slow and steady up from 1st all the way through 5th. Once in 5th w/ lean-burn, you would “drive with load” to maintain it. That is slowly decelerating on any uphill climb to maintain lean burn and slowly accelerating on the down slopes back to the target speed if there was no delta between initial and final elevations. This works very well with the non-hybrid’s too. Speeds ranged from 50 - 67 miles per hour depending on the down slopes length and grade. Maintaining a relatively steady band between 45 - 54 miles per hour on the flats would leave you highway legal but just barely. This was good for a usual 95 - 117 mpg depending on wind conditions in warmer late spring, summer, and early fall temps here in Northern Illinois.

Extreme Hypermileage Mode: Same accelerations and techniques but slower overall speeds. The record runs came about at 33 (DWL speed at crests) - 48 min/max speeds and driving at the absolute minimums out on rural highways. When driving locally, 33 - 35 miles per hour at just above idle would give a relatively steady 125 - 135 mpg but local roads are not conducive for this over a longer period given the lights, signs, and traffic to kill off momentum.

___Pulse and Glide with an IMA is not quite the same as your description for the Prius II. The following works for max FE also but it depends on traffic conditions. The Insight with a quick 1 - 2 - and maybe even into 3rd w/out assist and forced autostop for a long coast afterwards would yield excellent results but traffic jams are never conducive to let the glide continue to a stop nor was it practical over a given distance. I experimented with 1- 2 - 3 - forced autostops and coast to an actual stop on a country road out near my workplace late last year. With that, I could maintain 140 mpg over 5 miles but it wasn’t practical to coast all the way to a stop after each pulse. In heavy traffic using maximum buffers, pulse and glide was all I had and with it, I could maintain > 100 mpg but because there is never a uniform gap opening up in any acceleration phase nor regular distance before you actually did have to grab some regen nor heaven forbid, use the mechanicals, I could only very rarely increase my p[resent FE in the heaviest of traffic. It was a lot of work to simply maintain the current FE so I disliked driving under those conditions as do most for the more normal obvious “I hate traffic jams” reason.

___The pulse and glide technique that you described with the Prius II would not help the IMA equipped Honda’s imho because the ICE doesn’t shut down. That is unless through a forced autostop. Very few IMA or non-hybrid drivers use Forced Autostops to maximize FE but in heavy and still moving traffic, it is most certainly available for those with a stick in particular.

Gently rolling hills were never conducive to maximums with an IMA equipped hybrid in my experience. The flats at the lowest RPM’s and in the highest gear were however.

___And something extra … Straight drafts were relatively useless in the Insight because she really didn’t have the power at maximum FE (maintaining Lean Burn in fifth) to keep up with the continuous ebb and flow of the target when attempting to maintain a proper close in. When you did find an 18-wheeler at a steady 45 - 48 miles per hour on just the right section of roadway for whatever reason, you could peg the instantaneous at 150 mpg for however long the steady pace was maintained. Only on relatively flat terrain however. Traffic side drafts were the Insight’s godsend. Because of the slower speeds in the far right lanes vs. those in the middle and left lanes, the delta would help push her into a healthy average even when there was a headwind up to a max of maybe 10 miles per hour. Out in the open with a headwind, maximum FE was very painful to achieve. As wind speeds climbed, this would become maddening until you were at a point when you needed 3rd gear just to maintain highway speed. I do not know if you have ever driven in a 30 + miles per hour headwind in the Prius II yet but from my experience in the Insight, you do not want to do this … ever

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net