The real Trans-Am Series was created in 1966 by the SCCA as the Trans-American Sedan Championship. Originally derived from the SCCA's A Sedan (A/S) class, it featured purpose-built tube-frame race cars competing on road courses. The series was known for competition of muscle "pony" cars like the Ford Mustang, Chevy Camaro, Plymouth Barracuda, AMC Javelin and Dodge Challenger in the late 1960s and early 1970s, though marques from many different countries have competed in the series.

The early years were largely dominated by Mark Donohue, driving for Roger Penske. Penske campaigned Chevy Camaros through 1969, when he signed with American Motors to race the Javelin in 1970 and 1971. Donohue would chalk up 20 race victories between 1967 and 1970 and three unofficial drivers's championships, the third achieved in 1971. The 1970 Trans Am series is regarded by most racing historians as the high water mark of American road racing. Every "pony car" manufacturer was represented with a factory team and top driving talent: Chevrolet had the Chaparral Chevy Camaro Z28 team with Jim Hall, Ed Leslie, and Vic Elford. Ford's Bud Moore Boss 302 Mustangs were driven by Parnelli Jones and George Follmer. For Plymouth, the All American Racing Cudas were handled by Dan Gurney and Swede Savage. Sam Posey drove Ray Caldwell's Autodynamics Challenger TA, Jerry Titus had the Pontiac Trans Am, and Roger Penske's Sunoco AMC Javelin team starred Mark Donohue and Peter Revson.