Ford has introduced a heavily revised version of its Shelby GT500 range-topper for its latest model year. For the first time, Ford's Shelby GT500 is going to an all-aluminum version of the 5.4-liter supercharged V8 that was in the 2010 GT500. The latest Shelby GT500 will be the first modern Shelby without a gas guzzler tax, thanks to the EPA-projected 15 mpg city, and 23 mpg highway ratings.