[outlaw]

Originally Posted by biker1

Ethanol has 2/3 the energy of pure (ethanol free) gas and "regular" gas is 10% ethanol. Therefore, "regular" gas has 97% of the energy of ethanol free gas so you can expect 3% less mpg. If you are using a fuel that contains a higher percentage of ethanol then your mpg will be lower. Accurately measuring your mpg is not always that easy - there can be relatively large error bars on the measurement.

Thanks.