Starting with 1936, the Buick Special Series 40 model range represented the marque's entry level full-size automobile. The '36 was a very successful year for Buick and also marked the first time of using names rather than the simple serial numbers which had been in use before. The first Specials rode on a wheelbase, but for the next model year this was increased to as all Buicks grew for that year. The eight cylinder engine was also new, and was now of rather than . The Special (and all other Buicks as well) underwent a full restyling for 1939, with a more enclosed nose and a wider grille. The wheelbase was also two inches shorter.
For 1940, there was the usual restyle and the wheelbase increased by an inch. This was also the only model year that a four-door convertible Special ("Sport Phaeton") was offered, although only 552 were built. Prices started at US$795 ($ in dollars ) for the Business Coupe to US$925 ($ in dollars ) for either the 4-door Touring Sedan or 2-door Convertible.
For 1941 the bodywork was again all new, with the front fenders now very closely integrated into the cars overall design. The Estate Wagon migrated from being a Super into the Special lineup. A fastback was offered in Century and 40 Special trim as a four-door touring sedan and two-door business coupe and the 46S sedanette. Also new was the 40-A series (the regular Special now being the 40-B), a version on a three inches shorter wheelbase which shared its body with the 1941 Oldsmobile Series 70. These two series, with a restyle reminiscent of the 1939 Y-Job, continued into the abbreviated 1942 model year. Production ended on 4 February 1942. The Special was now offered as the entry-level luxury vehicle that the LaSalle previously held.
After production resumed, only the larger 1946 B-body Special range remained available, which is rare, representing less than two percent of Buick's production that year. The Special continued with minor changes until the prewar body was finally replaced halfway through the 1949 model year. Post-war Specials were only available as a four-door sedan or a two-door "sedanet", until the new 1949 models arrived.
In the movie Mildred Pierce, Veda Pierce, Mildred's daughter, played by actress Ann Blyth, was given a 1940 Buick Special convertible as a gift, valued at US$1,077 for the Model 46C ($ in dollars ). The engine remained the which had been used since 1937, but for 1951 this was replaced by the larger "Fireball" straight-eight.
The Special was available in both fastback Jetback and new notchback Tourback configurations. The Jetback was available as a 2-door Sedanet, 2-door coupe and 4-door sedan, whilst the Tourback was available only as a 4-door sedan. In 1950, overall 195,072 Jetbacks and 142,537 Tourbacks were produced, but just 72,735 Jetbacks were 4-door sedans, bit more than half of the Tourbacks. The fastback design, dating back to GM's pre-war streamliners, was quickly becoming outdated by the turn of the decade and by 1951, Special was no longer available in the Jetback style.
A two-door hardtop coupe was also new for 1951, but the unusual grille was revised with the grill bars shortened. The 1954 Specials had an all-new body and chassis, much wider and lower, and were now equipped with the all-new, more powerful "Fireball" V8 engines. In 1953 The Buick-Berle Show introduced product placement commercials on TV, and later in 1955 The Honeymooners was one of the sponsors.
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 pillarless hardtops ever produced. By then, the Buick Special was one of America's best selling automotive series, and is credited with helping Buick rise to #3 in sales, overtaking Chrysler's volume-seller Plymouth. For 1956 the larger V8 engine was shared with the rest of the range, although it was replaced by the bigger, 364 V8 for 1957. This year also brought all-new bodywork, as well as a four-door hardtop station wagon called the Buick Riviera Estate. The 1957 wheelbase remained 122 inches. In the June, 1957 issue of Popular Mechanics, the Special was rated with a 0-60 mph time of 11.6 seconds, fuel economy of at , and ground clearance of . 1958 brought the most chrome yet and twin headlights, as the car grew longer and wider, albeit on an unchanged chassis.
1949-1957 Buick Specials had three VentiPorts on each side while more senior Buicks (with the partial 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.
<gallery widths="200px" heights="150px">
File:1950 Buick Series 40 Special Sedan (25033623786).jpg|1950 Buick Special 4-Door Tourback Sedan
File:Buick De Luxe Tourback 1951 2.jpg|1951 Buick Special Deluxe Tourback Sedanette
File:1952 Buick Special DeLuxe Series 40D.jpg|1952 Buick Special DeLuxe Tourback Sedan
File:1953 Buick Special-2.jpg|1953 Buick Special Riviera coupe
File:1954 Buick 40 Special 2 door Hardtop - Flickr - Sicnag.jpg|1954 Buick Special Riviera coupe
File:Buick Special sedan ca 1955.jpg|1955 Buick Special 4-Door Sedan
File:1955 Buick Special Convertible.jpg|1955 Buick Special Convertible
File:Buick Special Station Wagon 1955.jpg|1955 Buick Special Estate Wagon
File:Goodwood Breakfast Club - 1956 Buick Special Riviera Sedan - Flickr - exfordy.jpg|1956 Buick Special 4-Door Riviera
File:1957 Buick Special 2 door Hardtop.jpg|1957 Buick Special 2-Door Riviera
File:1957 Buick Special Estate (22075340806).jpg|1957 Buick Special Riviera Estate hardtop station wagon
File:Buick Convertible 1958 2.jpg|1958 Buick Special convertible
</gallery>
1961–1963
In 1961, the car returned after a short absence of two years, but this time it was on the brand new unibody compact GM Y platform. The Special was powered by a innovative aluminum-block 215 in³ V8, and had Dual Path transmission and power steering. In mid-year a Skylark option was released with special trim, optional bucket seats and a four-barrel version of the 215 that made .
In 1962, the Special was the first American car to use a V6 engine in volume production; it earned Motor Trends Car of the Year for 1962. This 198 cid Fireball was engineered down from the 215 and used many of the same design parameters, but was cast in iron. Output was 135 hp (gross) at 4600 rpm and at 2400 rpm. In their test that year, Road & Track was impressed with Buick's "practical" new V6, saying it "sounds and performs exactly like the aluminum V8 in most respects." In 1963, the Special's body was restyled. Mechanically, however, the car was identical to the 1962 model. There was also some minor interior restyling, particularly to the dash and instrument cluster. The 1963 Special was available as a 2-door pillared hardtop coupe, a four dour sedan, a convertible, and a station wagon. Engine choices were a standard V6 with a twin-barrel carburetor and optional V8 with (two-barrel) or more powerful four-barrel ( in 1962, in 1963). Transmission choices were a three speed column shift manual transmission, a floor shift Borg-Warner T-10 four-speed manual, or a two-speed Turbine Drive
The 1963 body was only produced for one year; it sold 148,750 copies, including 42,321 Skylarks. The entire car was redesigned for 1964. After that, the 215 found its way into the Rover P6 3500S in 1968, but was never sold in North America in any great numbers. It was also employed in other British cars, including the Morgan Plus 8, MG MGB GTV8, Land Rover, and Triumph TR8, as well as retrofits into MGAs and MGBs. The engine had really earned its stripes as being the sole engine powering the Range Rover for a couple decades and eventually finding its way into the original Series/Defender Land Rover; and several other Land Rover Models including the Discovery and the Forward Control.
The Skylark became a separate series for 1962.
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File:1961 Buick Special (14482955232).jpg|1961 Buick Special 2-door sedan
File:1962 Buick Special DeLuxe.jpg|1962 Buick Special DeLuxe 4-door sedan
File:1963 Buick Special Convertible (18409526983).jpg|1963 Buick Special convertible
File:1963 Buick Special 4119.jpg|1963 Buick Special Deluxe 4-door sedan with factory 4-speed manual transmission
File:63 Buick Special (9131795376).jpg|1963 Buick Special Deluxe station wagon
</gallery>
1964–1967
The Special, along with the upscale Skylark, were redesigned for the 1964 model year with separate body-on-frame construction—renamed the A-body—and marketed as an intermediate-sized car. The Skylark was expanded to a full top-line series that now included two- and four-door sedans, two-door hardtop coupe and convertible, along with a station wagon. The other series models included the base Special and the slightly fancier Special Deluxe, in a more limited range of bodystyles.
Also new for 1964 were engines. The capacity of the V6 engine was increased from 198 to 225 cubic inches, while the aluminum V8 was replaced by a new cast iron-block 300 cubic inch V8 with aluminum cylinder heads. In 1965, cast iron heads replaced the problematic aluminum ones. This reliable engine, produced until 1967, was based on the aluminum V8, and many parts (such as the cylinder heads) were interchangeable.
<gallery widths=270px heights=180px>
File:64 Buick Special (14344479209).jpg|1964 Buick Special station wagon
File:1965 Buick Special.jpg|1965 Buick Special 4-door Sedan
File:1966 Buick Special Deluxe four-door Town Sedan, front left.jpg|1966 Buick Special Deluxe 4-Door Sedan
File:1966 Buick Special Convertible.jpg|1966 Buick Special convertible
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1968–1969
The Special nameplate was used on lower-priced intermediate-sized Buicks through the 1969 model year. In 1968 and 1969, the Buick Special was dropped and only Special Deluxes were manufactured. In 1970, the end of the Special came about when the Special Deluxe was dropped too in favor of the slightly upscale Buick Skylark.
The 1968 model year was one of significant change for the Buick Special and Skylark. Although still using the same basic chassis, all of GM's mid-sized cars adopted a policy of using two different length wheelbases. Two-door models used a shorter wheelbase of , while four-door models used a longer wheelbase of 116 in (the Buick Sport Wagon and Oldsmobile Vista Cruiser used an even longer wheelbase of 121 in). All of GM's mid-sized cars received all-new sheet metal, incorporating a semi-fastback appearance, which was a revival of a streamlining on all GM products from 1942 until 1950 as demonstrated on the Buick Super Club Coupe (sedanette). More Federally mandated safety features improved occupant protection and accident avoidance, including side marker lights, shoulder belts (on all models built after January 1, 1968), and parking lights that illuminated with headlights.
In a reshuffling of models in the lineup, the Special Deluxe replaced the previous Special. The Skylark nameplate was shuffled down a notch to replace the previous Special Deluxe. The previous Skylark was replaced by a new Skylark Custom.
The Special Deluxe was available as a pillared two-door coupe, a pillared four-door sedan, or a 2-row station wagon.
The previous V6 was discontinued and the associated tooling was sold to Kaiser Industries, which used the V6 in its Jeep trucks and sport utility vehicles. The base engine in the Buick Special (and Buick Skylark) coupes & sedans) became a Chevrolet I6, that produced at 4200 rpm using a single-barrel Rochester carburetor.
Optional on the Special Deluxe coupe & sedan and standard on the Special Deluxe station wagon was a new 350-cubic-inch V8 derived from the 340, using a two-barrel Rochester carburetor that produced at 4400 rpm. Optional on the Special Deluxe was a 350-cubic-inch V8 using a four-barrel Rochester carburetor that produced at 4600 rpm. The Buick Special name was dropped after the 1969 model year. A locking steering column with a new, rectangular ignition key became standard on all 1969 GM cars (except Corvair), one year ahead of the Federal requirement.
For 1970, the Buick Skylark name was moved down another notch, replacing the previous entry-level Buick Special.
thumb|left|1969 Buick Special Deluxe Wagon
1975–1977
thumb|1977 Buick Century Special
The Special returned briefly to the GM A platform as an entry level subseries of the Buick Century. Although officially sold as the Buick Century Special, it was sometimes also referred to as just the Buick Special.
Century Specials were usually powered by Buick's own 231 V6; a V8 (from either Buick, Oldsmobile, or Chevrolet) was offered but rarely optioned. It used the "colonnade" roofline but was fitted with a landau roof that covered most of the rear quarter windows. The opening that was left was the same shape as the windows on the higher series formal-roof cars.
1978–1979
200px|thumb|right|1978 Buick Century Special Fastback, with non-standard exhaust pipes.
In 1978 and 1979, the Special trim continued on the redesigned Century fastback and wagon models.
1991–1996
thumb|1992 Buick Century Special sedan
Special returned once again as the entry level trim on the Century sedan (starting 1991) and wagon (starting 1993). The "Special" designation was discontinued with the Century's redesign in 1997.