Doc Hudson had won three Piston Cups before the events of Pixar’s Cars.
Doc is introduced as the respected physician and judge of Radiator Springs, but his past is revealed as a legendary racing career. He won the Piston Cup in 1951, 1952, and 1953 while driving as the Fabulous Hudson Hornet.
His racing career ended after a crash and a long recovery. When he returned, the racing world treated him as obsolete and replaced him with newer competitors. Doc subsequently withdrew from racing and settled in Radiator Springs.
The character is based on the real Hudson Hornet, a car associated with early stock-car racing success. The Fabulous Hudson Hornet won the first three NASCAR Grand National championships, in 1951, 1952, and 1953, although the film adapts that history into its fictional Piston Cup world.