In Pixar's Cars, Doc Hudson is a 1951 Hudson Hornet and former Piston Cup champion. His hidden racing past makes him one of the film's most important mentors.
Doc initially presents himself as Radiator Springs' local judge and doctor. He distrusts Lightning McQueen's reckless attitude, but his knowledge of racing helps Lightning understand technique, patience, and responsibility. Doc eventually reveals that he won three Piston Cups before a crash ended his career and that the racing world moved on without honoring him properly.
The character is modeled partly on the real Hudson Hornet, a celebrated early-1950s stock car. In the film, Doc's number is 51, matching the year of the car model. Paul Newman voiced Doc Hudson in the first Cars film, making the role one of Newman's notable late-career voice performances. Doc does not appear as a living character in Cars 2, but his legacy and racing number remain important in Cars 3.