The original concept for the Mustang was the Mustang I, a prototype that never made it to production and has only recently been resurrected by the Ford Motor Company. The Mustang 1, which debuted at the 1962 Grand Prix, is as about as far from the popular production model as you can get. The pop culture image of the first Mustang is of the sporty, affordable car with an optional V8 engine which rolled off production lines 1964. The Mustang I has a boxy, wedge-like body with rear-wheel drive powered by a 4-cylinder engine located behind the driver. Small design pieces, such as the turn signals integrated into the bumper, were carried over. But in general, this Mustang 1 was a beast all its own.
Check out Autoblog's Mustang 1 gallery