DK wrote:
> Impreza 1993, EJ18 engine, manual.
>
> Exclusively city driving, average trip about 5-7 miles. Was trying to
> drive keeping RPMs close to 2,000 or to 3,000. For the most part
> in practice it meant choice between 4th and 3rd gear.
>
> Same pump, fuel contains "up to" 10% ethanol, same weather, two
> full tanks for each "condition". The milage was consistent between
> two tanks in each case within 0.3 MPG. Results:
>
> ~ 1,800-2,300 RPM = 26.7 MPG
> ~ 2,500-3,200 RPM = 28.1 MPG
> (No, EJ18 is not a marvel of fuel economy :-))
>
> Based on what I read before, I expected the opposite result. In any
> case, the difference is no more than 5%, so it's not really worth
> it to keep attention to. Lower RPM is less noise and less power.
> What's better for the engine in the long run?
>
> DK
>
>
Hmm,
2 tankful? Have you looked at power band curve of your eingine? And
frequency of brake use. My '98 Honda CRV alwasy produce 10L/100Km gas
mileage regardless of season or where I drive in the city. If you drive
your car most of time like that in the city better go out onto turnpike
and burn off all the carbon build up inside the engine.

Two things, every engine has optimum cruising rpm and speed by desing
which will give best efficiency. Of course this is based on sea level
driving. I live near Rockies at altitude of ~2700 feet.