Could this car have been one of the inspirations for Reg Hill’s design for Supercar from the Gerry Anderson TV series?
An image of the 1960 Cadillac Eldorado Fleetwood, taken from a Glenmorangie Scotch Whisky advert in 2011.
The 1959 Cadillac Eldorado Biaritz and 1960 Eldorado Fleetwood designs from General Motors are a possible source of inspiration for the Supercar design and were current cars around the time of Supercar’s creation. The 1959 and 1960 Eldorado side profile to the rear is similar to that of Supercar and its 192cm long fins closely match the shape of Supercar’s.
For further potential roots see http://www.aiai.ed.ac.uk/~bat/GA/supercar-origin.html
On that page there are details of the Ford FX-Atmos – a future experimental model created by Ford’s Advanced Design Studios for the 1954 Chicago Auto Show (see Wikipedia Article). This, I believe, is likely to be the main influence on Supercar’s design. Other concept cars of the 1950s may have been influential for some design elements (See Studebaker-Packard Astral).
YouTube: Ford Atmos, Ford Mystere and Studebaker-Packard Astral