The Chevrolet Cobalt replaced the aged design and reputation of the Cavalier in 2004. Just like its predecessor, the Cobalt is available as either a two door or a four door. New additions to the Cobalt lineup are polar opposites: the fuel-sipping XFE and the performance-minded SS. The Cobalt XFE gets highway fuel economy rated at 36 mpg, while the Cobalt SS gets a turbocharged, 260-horsepower engine in addition to noteworthy drivetrain, body and suspension improvements. The Chevrolet Cobalt comes with a five-year/100,000-mile powertrain and gets an estimated 30-36 mpg on the highway.