16-18 mpg if I stay off it, 10-12 if I don't.
Remember, there are a lot of variables in calculating gas mileage. The condition of your engine, the outside temperature, how much you idle, how much city vs highway driving you do and so on. I've seen 25 mpg on a long highway run all in fifth gear (with a 3.55 rear) and as low as 10 mpg when I've been cruising around town and stomping the gas pedal every few minutes while winding it out to the redline in every gear. On the average, with a little bit of energetic driving and a lot of 'normal' driving I see around 16-18 mpg in a stock 5.0 with a 5-speed and a 3.55 rear. Of course, neither I or anyone else buys a V-8 Mustang (or V-8
anything) for good gas mileage. If gas mileage was a real factor for us we would all be driving a Precis.
