Halfway into the 1949 model year, the Specials received all-new bodywork, the first fully post-war design for the series. New was also the 40D-series, a better equipped version called the Special Deluxe. The engine remained the 248 cu in (4.1 L) which had been used since 1937, but for 1951 this was replaced by the larger “Fireball” straight-eight. A two-door hardtop coupe was also new for 1951. The 1954 Specials had an all-new body and chassis, much wider and lower, and were now equipped with the all-new, more powerful “Nailhead” V8 engines.

Introduced in the middle of the 1955 model year the four-door Buick Special Riviera (along with the Century Riviera, the Oldsmobile 98 Holiday, and the 88 Holiday) were the first four-door pillar less hardtops ever produced. By then, the Buick Special was one of America’s bestselling automotive series. For 1956 the larger 322 cu in (5.3 L) V8 engine was shared with the rest of the range, although it was replaced by the bigger, 250 hp (186 kW) 364 V8 for 1957. This year also brought all-new bodywork, as well as a four-door hardtop station wagon called the Buick Caballero. The 1957 wheelbase remained 122 inches.

1949-1957 Buick Specials had three VentiPorts while more senior Buicks, with the exception of the Buick Super (which switched from three to four in 1955), had four. Earlier versions had a “Sweepspear” inspired character line alongside the body, while later versions had the “Sweepspear” moulding attached to the side of all models. GM renamed the Buick Special the LeSabre for the 1959 model year, taking the name from the 1951 Le Sabre concept car.