I dont expect an older mustang to have great gas mileage, but when I'm spending almost 10 dollars A DAY on gas, somethings up. All I know is that the check engine light comes on first through third gear, and the exhaust is kinda messed up at the moment. It gets 20-30 miles per quarter of a tank. The car is a daily driver, so I can't afford to spend this much gas, especially with the 4 dollars a gallon.