The late 1940s' through late 1950s' were indeed a (if not THE) "Golden Age" for U.S.-American automotive design. Spearheaded by the legendary Harley Earl, GMs' flamboyant chief of design, it was an era that was highlighted by dynamic forward thinking. Earls' concepts were a product of that spirit-as well as an unlimited budget afforded to him by GM (he was truy a "rock star" of the era). Some examples:
The 1951 (!!) LaSabre Concept. A landmark design exercise for GM.:
The 1954 Corvette Corvair concept. A fixed-roof, fastback GT sportscar. Not so common back then.:
The 1954 Buick Wildcat II. A more luxurious, "personal" adaption of the Chevrolet Corvette theme:
The 1954 Cadillac El Camino Concept. An early vision for a "personal" luxury 2 seat coupe.:
The 1954 Chevrolet Corvette Nomad concept. A shooting brake "Hollywood-style".:
The 1955 Buick Wildcat II Concept. Open grand touring of the highest order.:
The 1954 Corvette "Concept 58". It served as Earls' "personal coupe" for a short while. See the 1959 Cadillac and 1963 split-window Corvette Stingray coupe elements ?: