What speed will give me the best gas mileage? There's got to be a formula to find out at what engine speed (tach) vs vehicle speed gives me my best MPG. Is it the exact speed at which my car shifts into the highest gear? Or a little faster? I know there's a lot of other factors, but lets just say straight and level road, constant speed. Oh yeah, and ZERO with the engine turned off is not acceptable! - BCD
