There's never been a more fuel-efficient Mustang, and even the most powerful versions of the current car deliver decent gas mileage.By model, the Mustang's gas-mileage figures span a wide spectrum. Outfitted with the base 3.7-liter V-6 and a six-speed automatic, the Mustang is rated by the EPA at 19/31 mpg. Opt for the six-speed manual, and gas mileage falls slightly, to 19/29 mpg.
The GT's V-8 engine isn't the gas guzzler it's been in past versions. With the automatic, the EPA rates it at 18/25 mpg; with the manual, it scores a 17/26-mpg rating.
The Shelby versions with the larger V-8 engine can't manage the great fuel economy of other versions, but they're still rated at 15/23 mpg.