This post deals with a Ford concept car from those times, the Allegro that was announced mid-1963. Unlike a number of concepts from that era, it had production potential, being based on Taunus (German Ford) mechanicals. Since this was also a time when American firms were marketing what were termed "captive imports" -- cars brought over from their overseas affiliates -- it's possible that the Allegro was a test of a sporty Taunus, even though styling was done in Dearborn.
An interesting feature was its Ford Mustang-like front design that anticipated production Mustangs that were announced in April 1964. Actually, "anticipate" isn't really correct. The Mustang frontal design was essentially established by the fall of 1962, about the same time Allegro's design was finalized. So apparently the Allegro was a form of Mustang preview, and conceivably might have retained a Mustang feeling had it ever entered production.