In Pixar’s Cars, Doc Hudson raced under number 51 during his championship past.
The number 51 is shown on the blue Hudson Hornet connected with Doc’s earlier career. He is revealed to have won three Piston Cups before a crash ended his time as a top racer. His racing history explains why he is skeptical of Lightning McQueen’s fame and why he initially hides his own achievements.
Doc’s design draws on the real Hudson Hornet, a celebrated early stock car. The real vehicle became associated with NASCAR success in the early 1950s, including wins by drivers such as Herb Thomas. Pixar transformed that history into a fictional backstory for a retired character.
Doc’s number 51 is different from McQueen’s number 95. Both numbers are prominent in the film, but they belong to different generations of Piston Cup racing.