During the muscle car craze of 1960s and early 1970s, Buick nameplates weren’t known for powerhouse performance. The Hemi Roadrunner, Tri-Power GTOs, big-block Chevelles and 428 Cobra Jet Mustangs garnered the most reverence as fast cars capable of going faster in the right hands.

During the muscle car craze of 1960s and early 1970s, Buick nameplates weren’t known for powerhouse performance. The Hemi Roadrunner, Tri-Power GTOs, big-block Chevelles and 428 Cobra Jet Mustangs garnered the most reverence as fast cars capable of going faster in the right hands.

Buick, meanwhile, entered the high-performance fray with its mid-size 1965 Skylark GS (Gran Sport), featuring a 401-inch V8 (marketed as a 400) and 325 horses. These cars grew into street and strip prominence, as horsepower increased through the years with Stage I and Stage II engine offerings.

The fitting tribute came in 1970 when General Motors gave the green light to a 455-inch GS, with an even faster GSX model available for the ultimate thrill seeker. Two 455s were available, notably the 350 horse “normal” 455 that also came with the standard GS, or the 455 Stage I option that 400 of the lucky 687 GSX buyers that year purchased.

Only two colors were available in the 1970 GSX line, Saturn yellow or Apollo white. The GSX also sported special black stripes along the sides that ran over a special GSX rear spoiler, while the operating ram air hood featured black stripes and a hood mounted tachometer.

The Stage I engine found Buick engineers adding a higher lift cam and larger valve heads to produce 360 underrated horsepower with a single Quadrajet carburetor. Car experts agree that the Stage I 455 produced a minimum of 425 horses, as its torque rating of 510 lb. ft. is the highest ever for any muscle car of the era. The Stage I was only a $113 option over the standard 350-horse 455.

The proof of GSX’s superiority, however, came when a Stage I GSX, carrying 3,561 pounds of mass, scooted to 60 mph in just 5.5 seconds and ran the quarter mile on street tires in 13.3 at 107. These strictly stock numbers were better than many 426 Street Hemi Plymouths and Dodges, making the 1970 GSX one of the industry’s top “sleeper” cars of all time.

Today, a 1970 GSX at a Mecum or Barrett-Jackson auction will go for $125,000 or more, proving that the GSX is a collector gem where touches of Buick opulence mate with lethal horsepower.

Greg Zyla writes weekly on cars for GateHouse News Service. He welcomes reader inquiries at extramile_2000@yahoo.com or at 303 Roosevelt St., Sayre, PA 18840.

A GLANCE AT THE 1970 GSX

Colors: Saturn yellow or Apollo white
Number produced: 678
Stage 1: 400 of the GSX were Stage 1
Speed: 60 mph in 5.5 seconds
Price: Today they can go for $125,000 or more at auction