The 2011 Ford Mustang Shelby GT500 is powered by a 5.4 liter Dual Overhead Cam (DOHC) V8 engine that produces a whopping 550 hp at 6000 rpm and 510 lb-ft of torque at 4500 rpm. This is NOT a normally aspirated engine. Rather it is an intercooled, supercharged engine with 9 pounds of boost. Mileage is not the best with this beast of an engine, but with the standard 6 speed transmission, it is rated at 15 miles per gallon city and 23 mpg highway. The standard gearing in the differential is 3.55:1 in a limited slip axle.
Ford also offered the Performance Package for the 2011 GT500 for which you will receive a 3.73:1 limited slip differential. Also included n the package is 19 x 9.5 painted forged wheels with P265/40R19 front tires and on the rear are 20 x 9.5 painted forged aluminum wheels and P285.35R20 wheels. To go along with the power and traction options you get specially tuned rear springs and shocks. Visually the performance package adds a unique shifter know, classy striping, a gurney flap, a special spoiler and a underbody aerodynamic shield.