In Mustang's storied 50-year existence, numerous concepts and prototypes never made the jump to production. Over the decades, the Lee A Iacocca commissioned pony car has maintained its original characteristics of sporty affordability. Yet as everyone's favorite secretary's car evolved, plenty of ponies were sacrificed throughout the generations. Ford is celebrating these forgotten Mustangs, opening its archives ahead of the 2015's model expected debut at the 2014 New York Auto Show where it first took a bow.

In the early sixties Ford designers played around with sporty coupe themes based on the Falcon resulting in the Avventura, Avanti and Allegro, whose fastback profile was eventually adopted by the Mustang MkIII. The Allegro Design study was where the Stang's basic proportions: long hood, short deck, and compact greenhouse, were born. Two-seater studies followed along with the 1962 Mustang I, a mid-engine coupe concept that bore aesthetic cues of the 1966 GT40. In 1965, Ford produced a four-door concept, considered to be its first major styling faux pas, and in 1966 a station-wagon concept followed.

The Mach 1 and Mach 2 Concepts represented the last of the Sixties prototypes, and in 1970 the Mustang Milano broke cover in Chicago, whose extended nose found its way onto the 1971 model. The final three Mustang Concepts include the 1980 Ghia-penned RSX rally special based on the third-gen Fox-body Stang, the "Bruce Jenner" and "Rambo" concepts from 1990, and the 1992 Mach III Concept, which offered clues as to the fourth-gen's design direction.