In late 1955, NASCAR purchased SAFE (Society of Auto Sports, Fellowship, and Education), an all-convertible circuit known as the "Circuit of Champions All Stars." Most of SAFE's drivers did not make the transition when NASCAR absorbed and re-sanctioned the series. NASCAR then operated the Convertible Division from 1956 through 1959, during which convertibles occasionally shared grid space with Grand National hardtop cars in the same races.
The 1959 Daytona 500 illustrated the tension between the two formats: one qualifying race was reserved for Convertibles and one for the hardtop Grand National cars. Twenty of the 59 starters in that Daytona 500 were convertibles. This split qualifying format directly led to the development of what eventually became the Duel at Daytona qualifying races, which remain a fixture of Daytona 500 week to the present day.
The most prominent race associated with the Convertible Division was the Rebel 300 at Darlington Raceway, which evolved into the current Goodyear 400 NASCAR Cup Series event. As NASCAR's only superspeedway at the time, Darlington hosted the inaugural Rebel 300 on May 11, 1957, as a Convertible race. Rain forced the race to be completed the following Sunday, May 12, which drew a fine for promoter Bob Colvin for violating South Carolina blue laws.
The Rebel 300 was held as a Confederate Memorial Day Convertible race even after the division ended in 1959. Full Grand National points were awarded for three additional Convertible Division races from 1960 to 1962 at Darlington, won consecutively by Joe Weatherly, Fred Lorenzen, and Nelson Stacy (the latter winning on May 12, 1962, in the final Rebel 300 run under Convertible Division rules).
The Rebel 300 transitioned to a Grand National hardtop race in 1963, initially run as two 150-mile races before adopting a full 300-mile distance in 1964, expanding to 400 miles in 1966 and to 500 miles in 1974. The race reverted to 400 miles in 1994. It underwent various scheduling shifts across subsequent decades before returning to its traditional Confederate Memorial Day weekend slot in 2021 under the Goodyear 400 name, at 400 miles.
The Convertible Division produced four champions across its four seasons, all driving Chevrolet machinery:
1956: Bob Welborn (1956 Chevrolet)
1957: Bob Welborn (1957 Chevrolet)
1958: Bob Welborn (1957 Chevrolet)
1959: Joe Lee Johnson (1957 Chevrolet)
Bob Welborn's three consecutive championships made him the dominant figure of the division's brief existence.
Despite its short run, the NASCAR Convertible Division left two institutional imprints that outlasted it. The split qualifying system introduced at the 1959 Daytona 500 evolved into the Duel at Daytona, still used today to set the field for the Daytona 500. The Rebel 300 at Darlington, which began as a Convertible Division event, developed into one of NASCAR's longest-running Cup Series races through a continuous line of succession to the modern Goodyear 400.