1972 was the last model year for the mid-sized Buick Skylark. During this model year many pollution controls were added to the Engines, Compression was lowered, engines had to accept leaded and unleaded gas, and spark timing was retarded (no vacuum advance in lower gears) while driving in lower gears to reduce emissions. For 1972, the base Buick Skylark used the 350 cubic inch V8 with the 2-barrel Rochester carburetor (now putting out 145 horsepower) as standard equipment. A new federally mandated system to calculate power was put into effect that year, and the actual engine performance was probably comparable but slightly lower because of pollution controls in the 1972 model year to the 230 hp (170 kW) that was listed for the previous year. The Skylark 350 now used a version of the same V8 engine as the base Skylark, but with a 4-barrel Rochester carburetor that generated 170 hp (130 kW).
An interesting limited-production model was the 1972 Buick Skylark 350 Sun Coupe, which was a Skylark 350 Hardtop Coupe that featured a sliding vinyl sunroof, with a vinyl covering over the front portion of the roof (a landau design). Special striping and "Sun Coupe" badges on the rear pillars completed the package. Conversion work was subcontracted to the American Sunroof Company (ASC). Production of the Sun Coupe was approximately 3,950 units.
Skylark Customs were available with the same 350 cubic inch V8 engines available in the basic Skylark and the Skylark 350. The Custom had an upgraded interior and dash with some extra chrome. Convertibles only came in the Skylark Customs and the Skylark 350s.
Source: Wikipedia, 2012