The Shelby GT500 will get a new 5.4-liter, supercharged V8 engine with 550 horsepower and 510 pound-feet of torque.

The new engine provides a 10-horsepower increase versus the 2010 model and also is 102 pounds lighter.

Ford said that weight reduction will help to improve the iconic muscle car's fuel economy and driving performance.

The 2011 Shelby GT500 is expected to get 23 mpg on the highway and 15 mpg in the city — up from the 2010 model's 22 mpg on the highway and 14 mpg in the city, Ford said.

By exceeding 22.5 mpg, Ford can avoid the gas guzzler tax, a federal penalty that was put in place in 1978 to discourage manufacturers from producing inefficient vehicles.

"Cutting weight to improve performance is a tradition among hot rodders," Carroll Shelby, founder of Shelby American said in a statement. "It might not be as sexy as adding more horsepower, or bigger brakes, but shaving pounds off of a car is the single smartest move you can make."

Currently, Ford sells 10 versions of the Mustang, ranging from the Mustang V6, which starts at $21,395, to the Shelby GT500 for $51,725.

Last year, sales of the Ford's Mustang were challenged by the return of its nemesis, the Chevrolet Camaro.

Ford finished 2009 having sold 66,623 Mustangs, a 27 percent decline. Chevrolet sold 61,648 Camaros after the car went on sale in the spring for the first time since 2002.