What's your highest?
 

I've noticed that there's a maximum gas mileage in both automatics that I drive that around 42mph I can get 44 and 42 miles per gallon. This seems to be the lowest RPMs needed to not lose speed on flat ground at that speed, in the highest gear (4th).

What do you cars get?

Subary Legacy wagon - 44mpg
Chevy Venture van - 42mpg

EDIT: Just as clarification, I meant the highest for flat ground while on the accelerator, not the highest gas mileage using technique.

Hello!

I get 5 L/100km (47 MPG).

I haven't update my log recently, but I usually get in the mid 50s. I am hoping to break 60, but I am happy where I am at now.

edit: I have recorded on my gas log that my best tank to date was 59.99. Oh so close!!!

Andy, I think I can get about 6 LHK (39 MPG) when the road is flat and the winds are dead at around the same speed as you.

The tough part is finding those conditions to find out.

- no wind
- no grades
- no stops
- no traffic
- no chance around here at least

About 90 US MPG (2.7 L/100 km), at 80 km/h, on the flats in still air.....

30ish MPG @ 35 MPH

Flat ground: no wind, worn cement or new asphalt, 80*F, 70% Humidity.

'98 Integra Automatic (modified slightly)
IAT ~100*F
TPS ~15-16 (minimum = 9)
Speed ~ 45 mph
Full TC lockup, 4th gear, ~ 1800 RPM
FE ~ 47-50 mpg (until LOD changes as vehicle accelerates or decels -- not a whole lot of flat land here).

RH77

I'm not driving with an auto trans - but on the flat & holding pedal steady I've seen as high as 73 mpg (at 45mph) and 64 (at 55mph).Too bad that Columbus was correct in assuming the world was not flat...

GeekGuyAndy -

Stickshift, 46 MPG @ 42 MPH @ ~1440 RPM. This was at night in the fog in SoCal, so I think I would get a better number on a hot dry day.

EDIT : This was the average MPG from the SG over the span of one mile on the flat.

CarloSW2

I did another test last night and I got 2.5 L/100 km at 80 (on wide tires too), so call it 94 US MPG at a steady 50 MPH.

There is no flat ground nearby so I coast out of habit. But the best I've gotten keeping the car above 40 is about 38mpg, using 40mpg as top speed and gliding down to 20mph I was able to get it up to 47.55.

Maybe there is something wrong with my Subaru???:(

Mine is a 2.2L, maybe yours is the 2.5L version? I also disabled AWD on mine, but there are no other modifications

2001 Chevy Impala. 32 best, 31 highway, 28 overall. All at the max speed limit with the cruiz on (when possible).

https://www.lubedealer.com/T&SMay/

46 MPG, '06 Corolla with an AT. 80% at 65 mph

2.7L/100km over a 249.2 mile course, mostly repeated out and back loops on interstate with a semi-urban access drive to and from the start-finish and the highway. The 87.1 mpg on B100 biodiesel was converted to a BTU equivalent and then to a gasoline mpg equivalent to allow comparison of different fuels in the competitor's vehicles. The 2003 Tour de Sol official 83MPG(e) reflects this gasoline equivalent fuel efficiency.
Next best was 77+ mpg, again on B100, over a 500+ mile course in 2005.

Instant vs. Average
 

Friendly reminder to give the highest value at steady cruise, instead of long-distance averages :)