Cadillac Club Estonia

The 1953 Motorama showcar "Orleans" was the first 4-door hardtop concept car. Hardtop sedan construction eliminated the traditional "B" pillar, enabling a sleeker appearance. This styling innovation utilized frameless windows and was widely adopted throughout the industry. Buick and Oldsmobile introduced their production 4-door hardtops in 1955, but Cadillac waited until 1956 to introduce theirs.