what I do...and I do it quite often because I hate putting in gas, is if I drive early in the mornings I dirve with the windows down if I\'m in the city, then once I hit the freeway I roll up the windows but turn on the vents. I can usually make it to college without turning on the AC. Then on the way back I turn on the AC and turn the fan on full blast until the car gets cool, it takes maybe 2-3 minutes. Then I turn off the AC and just use the recirculate option on the fan.
I also use cruise control all the time, and try to keep my rpm below 3000 at all times. Also tefflon coated my car so it is more aerodynamic, and eggs won\'t stick to it.