7. Shelby Cobra GT 500-KR
Complex Says: The Shelby GT 500 was designed to put Ford's biggest engine into the Mustang. The problem was that only a few short months later, the absurdly powerful Cobra Jet engine was unveiled. Naturally, Shelby had to have it, so "KR" which stood for "King of the Road" was added as a suffix along with the new 7.0L V8.