Doc Hudson is revealed to have been the retired Piston Cup champion known as the Hudson Hornet.
In Cars, Doc initially acts as Radiator Springs' judge and physician and refuses to discuss his racing past. Lightning eventually discovers that Doc was once a celebrated racer who won three Piston Cups. His career ended after a crash and a long period of being overlooked by the racing world.
The character is based on the real Hudson Hornet, a car associated with the early 1950s Hudson automobile company and its success in stock-car racing. The real Hudson Hornet became famous for its “Fabulous Hudson Hornet” identity and for victories in early NASCAR competition.
People sometimes answer “Fabulous Hudson Hornet,” which is a related nickname, but the canonical make-and-model name used for Doc's racing identity is Hudson Hornet. Paul Newman provided Doc's voice in Cars and Cars 3 through archival material.