GM, including engineering and technical support in the development of the car and its automatic transmission (this is evidenced by the similarity between the Chevy Corvette GS-II "research and development" model and the Chaparral 2A through 2C models). First raced in late 1963, the Chaparral 2 developed into a highly competitive car in the Can-Am series in 1966 and 1967. Designed for the 200-mile races of the Can-Am series, it was also a winner in longer endurance races. In 1965, it shocked the sports car world by winning the 12 Hours of Sebring in a pouring rainstorm, on one of the roughest tracks in North America. The Chaparral 2 featured the innovative use of fiberglass as a chassis material. The Chaparral 2C had a conventional aluminum chassis. It is very difficult to identify all iterations of the car as new ideas were being tested continually. The 2A is the car as originally raced, featuring a very conventional sharp edge to cut through the air. It also featured a concave tail reminiscent of the theories of Wunibald Kamm. The first aerodynamic appendages began to appear on the 2A almost immediately to cure an issue with the front end being very light at speed with a consequent impact on steering accuracy and driver confidence. As the car evolved, it grew and changed shape. Most call these 2B and were raced through the end of 1965. The 2C introduced the innovative in-car adjustable rear wing. The integrated spoiler-wing was designed to lie flat for low drag on the straights and tip-up under braking through the corners. The car's clutchless, semi-automatic transmission kept the driver's left foot free to operate the wing mechanism. The 2C was based on a Chevrolet-designed aluminum chassis and was a smaller car in every dimension than the 2B. Without the natural non-resonant damping of the fiberglass chassis, Hap Sharp nicknamed it the EBJ — "eyeball jiggler". Alongside the development of aerodynamics was Hall's development of race tires. Jim Hall owned Rattlesnake Raceway, located adjacent to his race shop; its proximity allowed him to participate in much of Firestone's race tire development. A two-article series in Car and Driver magazine featured Hall's design theories, turning speculation about vehicle handling into applied physics. Hall's theories were the precursor to the elaborate data collection and management of current racing teams. The 2D was the first closed cockpit variant of the 2-series, designed