Mustangs grew larger and heavier with each model year until, in response to the 1971-1973 models, fans of the original 1964 design wrote to Ford urging a return to its size and concept.
Although some other pony cars have seen a revival, the Mustang is the only original pony car that has remained in production without interruption after four decades of development and revision.
Main article: First-generation Ford Mustang
Conceived by Ford product manager Donald N. Frey and championed by Ford Division general manager Lee Iacocca, the Mustang prototype was a two-seat, front-mounted engine roadster. This would later be remodeled as a four-seat car penned by David Ash and John Oros in Ford's Lincoln–Mercury Division design studios, which produced the winning design in an intramural design contest instigated by Iacocca. To cut down the development cost and achieve a suggested retail price of US$2,368, the Mustang was based heavily on familiar yet simple components. Much of the chassis, suspension, and drivetrain components were derived from the Ford Falcon and Ford Fairlane (North American). Favorable publicity articles appeared in 2,600 newspapers the next morning, the day the car was "officially" revealed. A Mustang also appeared in the James Bond film Goldfinger in September 1964, the first time the car was used in a movie.
Original sales forecasts projected less than 100,000 units for the first year, but in its first eighteen months, more than one million Mustangs were built.
Main article: Second-generation Ford Mustang
The 1970s brought about more stringent pollution laws and the OPEC oil embargo. As a result, large, fuel-inefficient cars fell into disfavor, and the Pony Cars were no exception. Lee Iacocca, who became president of the Ford Motor Company in 1964 and was the driving force behind the original Mustang, ordered a smaller, more fuel-efficient Mustang for 1974. Initially it was to be based on the Ford Maverick, but ultimately was based on the Ford Pinto subcompact.