Hm that is strange, i will try my best to help you figure this out. Do you have any mods done? What type of fuel are you running from what company? Are you real heavy on the go pedal? Also have you made sure everything is running good. Air filter is clean/ maybe do a run of sea foam to clean out any carbon buildup. I am running 35" mt tires and avg alot better then that. My biggest mpg gain would have come from my tuner and running better tunes then stock.