Topic: Fuel Economy

[06CoolSolstice]

Has anyone else experienced this?  On the way back from Nationals I was driving on the flat desert and noticed something funny.  At 60 mph my fuel economy was actually lower than if I drove about 77 mph.  77 seemed to be the optimal speed as above 80 it started to fall off.  Not being an engineer the only thing I can think of is our cars are more aerodynamic and more efficient at the higher speed than a sedan.

[Kelu]

I think is more about engine, what rpms?

What was actually the difference mpg between the 2 speeds?

Small invisible declined road?

Both moments on cruise control?

[Sol Asylum]

Aerodynamics shouldn't change with speed.  Now maybe if you were drafting behind another vehicle that might change things and if you went from a head wind to a tail wind that will improve things too.

[Gentleman Jack]

Did you use a shrink ray?

[Sol Asylum]

Did you use a shrink ray?

On Elff?

[06CoolSolstice]

I  do not remember the rpm I was running at.  It was around 5am no other cars around on flat road.  I was getting 29 mpg at 80 mph, and 27 mpg at  60 mph.

[ophidia31]

Aerodynamics shouldn't change with speed.

No, but the air flowing over the vehicle and where that air goes does change with speed.

I average 28mpg at 70mph when I take trips. At that speed, Im usually lugging along at a little under 3k rpm. Maybe 2800-2900rpm. At around 80mph Im up around 3100-3200rpm.

Also, our cars are far from being the poster childs of aerodynamics or fuel efficiency. For a modern 4cyl in a small car, we should be 35mpg. But since our cars are more show than flow, it suffers.

[1LILNDN]

According to my gas slips and miles driven W/cruise control on most of the time it says I averaged 27-31MPG . Most of the time I was doing around 65-80 and that was with 91 Octane until mid Ohio then 93 to MD

[Critterman]

I get 30-31 between 55-65 on my 06.