Ford began offering the 428 cubic inch (7.0L) Cobra Jet engine in 1968. This engine was very popular among drag racers thanks to its 335 hp rating.

The 1968 Mustang was used in the movie Bullitt and helped propel the fastback style to cult status. The car used in the movie was a Mustang GT fastback with a 390 cubic inch engine - as is typical of cars used in movies and television, it also had other modifications.

For the Shelby Mustangs, the 289 engine was replaced by a 302 cubic-inch engine in the GT350. The GT500 with its 428 engine continued as well and a special GT500KR (the KR stood for “King of the Road”) with a tweaked 428 Cobra Jet engine saw limited production.