In 1955, Buick and Oldsmobile introduced the first four-door hardtop sedans, and in 1956 the first four-door hardtop station wagon was introduced by Rambler.
Buick and Oldsmobile introduced the first four-door hardtop sedans. This was in 1955. The first four-door hardtop station wagon was introduced by Rambler. This was in 1956. This was in 1955.