General Motors lifted its 400-cid limit on its intermediate cars in 1970. That unleashed some of the quickest automobiles ever to come out of Detroit and helped make this the pinnacle year for American muscle. At the forefront to the rush to power was Buick. Its performance offering was again based on the midsize Skylark which got fresh styling that added two inches of body length on an unchanged wheelbase for 1970. Replacing the GS 400 and its 400-cid V-8 was the GS 455 named for its new 455-cid V-8 rated at a very conservative 350 bhp and an incredible 510 lb-ft of torque (at 2800 rpm).
Standard on GS models were functional hood scoops that mated to dual air-cleaner intakes. For those wanting more power Buick offered the 455 Stage 1 performance package. Its tweaks included a hotter cam even larger valves and stronger springs plus a revised carburetor jetting. Torque was unchanged and Buick slyly put horsepower at 360 but most testers said it was closer to 400. A bargain at just $199 the Stage 1 package included a Positraction axle and performance modifications to the manual and automatic transmissions. During the model year Buick unveiled the ultimate expression of its ultimate muscle car the GSX. It added $1196 to the GS 455 and came in either Apollo White or Saturn Yellow set off by unique stripes and spoilers.
The GSX package included a hood mounted tach Hurst-shifted four-speed (or Turbo-400) Polyglass G60x15s on seven-inch-wide chrome wheels front disk brakes and heavy-duty suspension. A 13.38-second pass at 105.5 mph prompted Motor Trend to crown the GS 455 Stage 1 "the quickest American production car we had ever tested." Most other magazines posted times in the high 13s. Any way you cut it Buick had earned its place on muscle car's all-time all-star team.
