In 2011 the Mustang GT has decent MPG ratings, especially considering it is boasting a hearty 5.0L V8 engine with 412 HP. Both the GT, and the GT Premium, rate the same in regards to fuel consumption. Each gets 16 MPG in the city while earning 26 MPG on the highway. Not bad numbers for the lighter engine. Ford has really done its homework on this one and the lighter car, combined with an increase in technology has allowed the Mustang to boast respectable fuel numbers while maintaining power and quickness.