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 Fleetwood Sixty Special Brougham d'Elegance in 1973 and the Fleetwood Sixty Special Brougham Talisman in 1974, both offered as a single trim package below the Series 70 limousine. The Sixty Special name was temporarily retired in 1976, returned in 1987, and continued through 1993.

1938–1941

In 1938 the Harley Earl-Bill Mitchell designed Sixty Special replaced the Series 65, slotting it between Cadillac's entry level line, the "Series 60", and the "Senior" large-bodied Series 70 Cadillacs. 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.Odin, L.C. World in Motion 1939 - The whole of the year's automobile production. Belvedere Publishing, 2015. ASIN: B00ZLN91ZG.

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 , V8 engine.

In its debut year, 3,703 Sixty Specials were delivered, at a base cost of US$2,090 ($ in dollars ) - it was a success in every measure. The new Sixty Special outsold every other Cadillac model in its first year accounting for 39% of all Cadillacs sold. In 1938, aside from the standard 4-door sedan, two prototype models were built on the Sixty Special body - two very dashing four-door convertibles (one owned by GM executive, Larry Fisher, which was demolished by Harley Earl in a traffic accident and one sent to Europe, which was later recalled and consumed by GM Engineering in structural tests in preparation for the 1940 "Torpedo" bodies), plus one Sixty-Special coupe (driven personally for two years by GM President, Bill Knudsen).

A not well-received new front end, which was patterned on the Lincoln Zephyr and lacked the visual punch expected by Cadillac buyers, a modest change in trim level, and some new options appeared for Sixty Special in 1939. First among the new options was a retractable metal panel above the front seat called a "Sunshine Turret-Top Roof", a predecessor to the type of sunroof that would not become more commonplace until the mid-1970s. The sliding roof, patented by GM's Ternstedt Hardware division, was unlatched and slid back into a recess built into the rear portion of the main roof where it would lock in place. Second was an optional retractable division glass in between the front and rear seats. This partition did not have a header in the roof, only channels between the door posts for the retractable glass to travel. The 1938 price of $2,090 remained for 1939 as well. More than 5,500 Sixty Specials were built for 1939, accounting for 40% of all Cadillacs sold, but only 280 of them were equipped with the sun roof option (of those 280 sun roof optioned cars, 55 of them were also equipped with the retractable glass partition). Special orders in 1939 included a convertible sedan built on the Sixty Special chassis for Prince Frederik of Denmark.

Starting in 1940, and for the remainder of its existence, the Sixty Special would be Fleetwood marketed, enjoying higher-priced molding, trim and upholstery like the Series 75 and 90. Thus it took over the Series 70's place, which was dropped for the 1938 model year, as Cadillac's most luxurious owner-driven large model, a role it would fill through 1976. For 1940, the price (for the third year in a row) and general styling remained the same, with only modest trim changes. Of special note is that 1940 was the last year that side-mounted spare tires (optional on all Cadillacs, including Sixty Special) were offered. The Sixty Special line expanded to four models this year: Touring Sedan (the base model), Imperial sedan (priced at $2,230, it featured a retractable glass partition between the front and rear seats), and two open-front Town Car models (one style with a painted roof, the other with a leather-covered roof). These two very formal cars had a removable roof section over the front seat and a glass division window. Of the Sixty Specials built in 1940, 4,242 of them were the Touring model. There were 113 Imperials (including 3 that were also equipped with the sun roof), and lastly, only 15 Town Car models. Of the 15, 9 had the painted metal roof (priced at $3,465), and 6 were the formal leather-covered roof version (priced at $3,820).

1941 was the last year of Harley Earl and Bill Mitchell's original Sixty Special design, as an all-new 1942 model was in the works. Many consider the 1941 to the most beautiful of this series, though Mitchell himself favored the clean lines of the original 1938 model. For the first time, Cadillac had its own front end design—the wider than high "tombstone" grille with a forward-jutting center section flanked by flat side sections — that would identify Cadillacs for years to come; the new grille appeared as a horizontally-oriented rectangle when viewed head-on hence the nickname. Other changes were longer front fenders that terminated with extension caps attached to the front doors, fully engulfed the lowered, widely positioned headlights and (in concert with a new hood) filled the formerly vacant area adjacent to the engine compartment; the rear fenders now held full skirts as standard. For 1941, the wheelbase was reduced by , down to . Sixty Specials showed a $105 price increase (for the first time) to $2,195. Power was still supplied by the same Cadillac engine as before, but was now rated at . Production totals include 3,878 Touring sedans (including 185 with the sun roof option), and 220 Imperial sedans (now priced at $2,345). Only 1 Sixty Special Town Car was made this year and used on the auto show circuit before being purchased by film director, Cecil B. DeMille. Featuring the leather-covered roof, it was the last one to come from Cadillac-Fleetwood.

There were nearly 17,900 Sixty Specials made from 1938 to 1941, including about a dozen custom bodied versions.

1942, 1946–1947

The Sixty Special for 1942 was longer and lower than the 1941 model, and now riding an exclusive wheelbase of , longer than any other non-limousine Cadillac. It was a central characteristic of the Sixty Special. For 28 of the next 34 model years of its existence, the Sixty Special featured a uniquely stretched GM C-Body with greater legroom and headroom.

Through 1948, Cadillac advertised the Sixty Special as a five-passenger car. The new design was more streamlined and less upright in appearance versus its predecessor, featuring "pontoon" fenders front and rear; this was the year that the bumper "bullets" were introduced which would remain a Cadillac styling feature through 1958. The unique, separate bright metal window frames were dropped in favor of bright metal window surrounds on conventional style doors. The slow-selling Sunshine Roof (sun roof) option was discontinued at the end of the 1941 model year, and would not reappear in a Cadillac until the 1970 Eldorado. Rear compartment wood-grained door caps now blended into a fixed rear bulkhead just behind the front seat (on all vehicles with or without a glass partition), emphasizing front and rear compartment separation. While the model-specific interior was luxuriously outfitted, Cadillac largely depended on trim to differentiate the exterior of Sixty Special from the shorter but similarly styled Series 62 Touring Sedan. Decorative chrome louvers - which would become a Sixty Special trademark ornament for years to come - were mounted in three locations on the 1942 model: behind the wheel well openings on the front and rear fenders, as well as mounted on the roof behind the rear door opening. In addition to the louvered trim, the Sixty Special had a wider "C-pillar" than other models. Just two variants were now available in the Sixty Special series – the standard sedan priced at $2,435 and a $2,589 Imperial sedan which featured an electrically adjustable glass partition between the front and rear seats. Productions totals include 1,684 standard sedans and an additional 190 Imperial sedans. Because of World War II, Cadillac ended automobile production in February 1942 and began assembling military equipment.

The 1946 Sixty Special was now very similar to the C-body Series 62, though a mild wheelbase stretch added more room to the rear seat area. The 1946 model showed few changes from the 1942 model, including a mild grille redesign and new bumpers. Parking lamps and turn signals were now mounted below the headlights. This was the first year the "V" was used underneath the Cadillac crest (the last vehicle to use this emblem would be the 1984 DeVille). Only one model remained in the Sixty Special lineup – the $3,054 standard sedan. Both sets of fender-mounted chrome louvers were gone, but roof-mounted ones remained. Cadillac now used a negative-ground battery on a 6-volt system. Sixty Special would only reach 5,700 units for 1946, as it did not go into production until later in the model year. An electric clock was standard.

Few changes greeted Sixty Special for 1947, as an all-new design was coming in 1948. Cadillac's famed "sombrero" wheel covers – in bright stainless steel - debuted this year. Behind the redesigned grille was the same engine that Cadillac had been using since 1936, now rated at . Bright metal stone shields – mounted on the forward edge of the rear fenders - replaced the black rubber pieces used on the 1946 model. The new grille was made up of five bars versus the previous six. Lastly, Cadillac script nameplates replaced the block letters used previously. Price was up to $3,195 – a pretty substantial jump from the 1942 price of $2,435 considering it was practically the same vehicle. Despite the steep price hike, production hit a new height at 8,500 units, but this represented only 14% of Cadillac's sales, down sharply from the 40% share they had represented in 1939. This was largely due to the tremendous sales success of the Series 62, whose low bodies with broad shoulder room and no running boards had been inspired by the original Sixty Special.

1948–1949