i get 25 - 27mpg on mine, tire size seems to make little difference. bing carburated and old, thats not too shabby. IMHO a 660cc engine is just way too small for a truck. It was barely big enough on my old honda shadow motorcycle! Thus the engine over works itself and doesnt make the numbers on fuel econ like it could. Kei class should up the engine size so they can get better econ.