Optimum speed for best MPG, Anybody? Options

[Legit94GT]

So every car has an optimum speed to achieve the best MPG, I am curious if anyone knows what the optimum speed is for our celicas?

Both 5SFE and 7AFE. I know there is an acutal formula to figure it all out, but i dont have it anymore:(

thanks

[FAQdaWorld]

This is something I've always wondered about...

Shouldnt we be achieving the best mpg when the engine is at the lowest possible rpms while in the highest gear without bogging the engine?

For example cruising at 40 - 45 mph in 5th gear I'm guessing is around 1.5k rpm and should in theory be burning less fuel per mile than it would at 55 mph at 2k rpm?

I have one buddy that insist that no that's not true but at least with my current understanding of how EFI works it makes sense to me and that the 55mph speed limit is actually pretty arbitrary and a generic 'efficiency point'.

Anyone want to correct / verify this?

[azian_advanced]

Shouldnt we be achieving the best mpg when the engine is at the lowest possible rpms while in the highest gear without bogging the engine?

x2. driving at the lowest rpms at the highest gear while depressing the gas pedal as little as possible to keep it driving at a steady speed without bogging the engine is how you'll achieve your best mpg. higher rpms will increase gas consumption (while rpms are directly proportional to speed while on the same gear, gas consumption is not directly proportional to speed) and driving faster will just increase air resistance (unless you're getting tail wind faster than your driving speed). just my opinion, not sure if this is exactly true.

This post has been edited by azian_advanced: May 8, 2009 - 10:47 AM