What do you guys drive with, the overdrive on or off and which gets better mileage. I thought by turning it off I would get better mileage but the rpms are higher with it off so I'm not sure anymore.

 

You should ALWAYS drive the the overdrive on. The only time you need to turn it off is if your at the track (which it shouldn't even go to O/D), towing (probably not going to happen), or in snow (maybe IDK). Overdrive is just like the 4th gear. Driving with it off would be like me driving 75mph down the interstate in 4th gear.

 

If your worried about MPG's Sell the Mustang and buy an Electric car