@starlene: If you look closely or full-size it you see it`s a 4dr hardtop.

In 1956 the Series 62 Coupe de Ville was joined by the Series 62 Sedan de Ville, Cadillac's first standard production 4-door hardtop. Similarly to the Coupe de Ville, it was also more expensive and more luxuriously trimmed than the standard 4-door Series 62. With 41,732 sold, it also easily outsold the Series 62 sedan in its very first year. From Wikipedia.

No, it’s a coupe de ville

1956 Cadillac Sedan de Ville