Ford manufactured the first Mustang fastbacks in September 1964. However, sales of fastbacks to the public did not begin until the company released the 1965 models.
Mustangs fulfilled a vision of Lee Iacocca, who in 1964 was Ford's general manager. Although intermediate-sized muscle cars were popular at the time, Iacocca believed the next big thing would be a small sports car. He decided that, instead of improving Ford's underwhelming intermediate muscle car, the company would introduce a new kind of automobile.
Two million Mustangs sold in the first two years of production. Sales in 1966 suggest fastbacks were actually the least popular of the three styles available, with half a million hardtops sold compared with 70,000 convertibles and 35,000 fastbacks.