Ford added a fastback to its 1965 Mustang lineup, but the coupe continued to be the best seller of the group. The coupe outsold the convertible and fastback individually five to one, accounting for nearly 75 percent of total sales.

The first Mustang GT was introduced in April of 1965. They were available in all three body styles. Two optional V-8 engines were offered with the GT with either 225 or 271 hp and a choice of a three- or four-speed manual, or a Cruise-O-Matic transmission. The '65 GT also included a special dashboard instrument cluster that became standard in 1966. The GT had stripes on the lower body sides, fog lamps in the grille, dual exhaust tips, and GT badges on the front fenders. The GT upgrade was an extra $165.03.

An interior upgrade was available for 1965 and 1966 Mustangs. The Deluxe or "Pony" Interior included two-tone seats with running horses stamped on the backs.

The first Shelby Mustang was introduced in 1965. They were all fastbacks with no rear seat and the spare tire mounted under the rear windshield. The 289 was hopped up to 306 hp. They were all Wimbledon White fastbacks with black interior and Guardsman Blue stripes. The fuel door wore the pony & tribar Mustang enmblem.

Unique Performance began making Shelby G.T. 350 SR Mustangs in 2004. The cars were built using 1965 and 1966 fastbacks, but modern engine and suspension technology. The first unit produced sold at the 2004 Barrett-Jackson Auction for $151,200. Unique Performance also makes 1967 Shelby G.T.500 "Eleanor" replicas.

1964's Goldfinger was the first major motion picture to show a Mustang. James Bond drove an Aston Martin DB5 while chasing Tilly Masterson in a white 1964 1/2 Mustang convertible. Bond's center caps popped out and became spinning blades, which slashed the Mustang's tires and destroyed the body panels. There was also a gold fastback created for the movie, but it wasn't ready in time for production. Check out The Pony Site for pictures and information on the car.

Thunderball also showed a Ford Mustang; Fiona Volpe drove a Sky Blue 1965 Mustang convertible.