I'm running 37's and 5:13's with an auto. In town my average is 13.9 mpg. If I baby it and not use the skinny peddle a lot I'll get 15 mpg. On the highway, if I set the cruse I can get 20 on flat ground. Now that being said, if I try to drive 85 in the mountains it drops down to 11-13 mpg...