The Fabulous Hudson Hornet is painted with racing number 51 in Pixar’s Cars.
Doc Hudson’s number connects him to the real Hudson Hornet, a car that became famous in early American stock-car racing. In the film’s backstory, Doc wins three Piston Cups before a crash ends his racing career. He later becomes the local doctor and sheriff-like authority of Radiator Springs, keeping much of his former identity private.
The number 51 is a visual clue to Doc’s past. Lightning eventually learns that the quiet town doctor was once a champion, which changes how he sees Doc and helps transform their relationship from hostility into mentorship.
The number is easy to confuse with Lightning McQueen’s 95, which appears prominently throughout the films. It is also different from the number 43 associated with real NASCAR champion Richard Petty, whose voice and racing image influenced some Cars material.