The Cadillac Sixty Special is a name used by Cadillac to denote a special model since the 1938 Harley Earl–Bill Mitchell–designed extended wheelbase derivative of the Series 60, often referred to as the Fleetwood Sixty Special. The Sixty Special designation was reserved for some of Cadillac's most luxurious vehicles. It was offered as a four-door sedan and briefly as a four-door hardtop. This exclusivity was reflected in the introduction of the exclusive Fleetwood Sixty Special Brougham d'Elegance in 1973 and the Fleetwood Sixty Special Brougham Talisman in 1974, and it was offered as one trim package below the Series 70 limousine. The Sixty Special name was temporarily retired in 1976 but returned again in 1987 and continued through 1993. 1938–1941 For 1938, the Harley Earl-Bill Mitchell designed Sixty Special was added between Cadillac's lowest-priced line of cars, the "Series 60", and the "Senior" large-bodied Cadillacs and it replaced the Series 65. Although all first-generation 60 Specials were built at the Fleetwood Plant, the 60 Special was marketed as a Fisher Body car in 1938 and 1939. The new four-door sedan, designed to look like a convertible sedan, showcased trend-setting features including a completely integrated, coupe-like trunk (which launched "three-box" sedan styling); no running boards (which all makes soon followed); convertible-style doors with bright metal window frames (Bill Mitchell called the '38 60 Special "the first hardtop"); a "four-window" canopy with more glass area than any Cadillac before; a steeply-raked windshield and four front-hinged doors. Contrary to what was then prevailing practice for luxury automobiles, the new Sixty Special was intended as an owner-driven car, rather than a chauffeur-driven one. It was built on a wheelbase - longer than the standard Series 60 cars. The new Sixty Special utilized a unique "X" frame underneath, which allowed the . car to sit within its frame. This not only gave the new Cadillac the stiffest chassis on the market, but it was also 3 inches lower than other Cadillacs - with no sacrifice in headroom. The disappearance of running boards along the side and its lack of a heavy belt line molding made the sleek car appear even lower. More important, it allowed shoulder and hip room to increase by over 5 inches without an increase in overall width. When combined with the brand-new column-mounted shift lever, the cars offered true six passenger comfort. The Sixty Special was powered by Cadillac's standard ,