I have complete confidence that if I was doing all highway, I'd be seeing 36 to 37 MPG. My best highway mpg to date was 33.xx mpg to Louisville and back w/ windows up, A/C used the entire trip, tires at door jamb spec (26 front 28 rear I think?) one passanger, cruise control used the entire trip, and ambient temp was 90*F both ways. That was 2 years ago when the car had all kinds of bugs and before I knew about hypermiling. My best mixed tank back then was 27 mpg...
Advance to today, my most recent mixed tank was probably 90% city and got 31.xx mpg. That's 4mpg improvement over 2 years ago. Even though it's not realistic, lets just say I get 4mpg improvement on my best highway tank, that would land a solid 37mpg.
If the boldface is true, then I think this could be a large factor in P&G not working for you and your overall frustration with your mpg. I have my tires at 55-60psi which makes a world of difference. Of course my car isn't safe to drive at this pressure, but it sure saves on gas and makes P&G very worthwhile since it extends the glide so far. With your tire pressure, your glide is not lasting long enough to make up for the fuel used pulsing. You are pulsing too frequently and your glide is not lasting long enough for it to pay off.
What does the max PSI on the tires say? I think you would be better off inflating your tires to about 3psi higher than what the max says on the tires. Keep in mind you generally want more pressure in the front than the back when the back is lighter than the front. I wouldn't be surprised if your tires wore out less, were just as safe (possible slight loss of traction in wet--but you should find a wet parking lot and test it out) and your FE would jump dramatically. I don't understand the logic of going by what it says on the door jamb. Does the door jamb know what kind of tires you have on the car?
I upped the tires pressure about a year and a half ago to sidewall, and since joining this site I've taken them from 44 to 48, and for my recent trip, I put in 50psi cold.
I don't think P&G works much for me because on my daily commute, there just isn't much opportunity for it. To work it's mostly slight inclined roads or twisty roads which, although I love feeling the G's I have to respect my car has 140k on the stock shocks/springs.... and the trip home I have LOTS of P&G opportunity, but cannot take advantage of any of it due to traffic.
1. It's a manual
2. he has lightweight rims on it
4. IDEAL location. CleanMPG held this competition at his house.
5. extensive use of EVERY technique that's documented.
6. some extra mojo-factor. I'm doing my best, driving very much the same way, and I can't touch him.