Doc Hudson is the Pixar Cars character based on the Hudson Hornet, a real champion stock car.
In Cars, Doc is revealed to be the Hudson Hornet, a legendary racer who won three Piston Cups before a crash ended his career. The character’s history echoes the real Hudson Hornet’s success in early stock-car racing. Hudson Hornets dominated NASCAR competition in the early 1950s, including multiple championships associated with driver Herb Thomas.
The film does not present Doc as a literal historical vehicle. Instead, it turns the Hudson Hornet’s reputation into a fictional character with memories, regrets, and a mentoring role. His experience helps Lightning McQueen learn that racing is not only about speed or publicity.
The King is based on a Plymouth Superbird and is voiced by real racing star Richard Petty, while Chick Hicks is a fictional green racer modeled broadly on aggressive stock-car rivals. Those connections can make the answer confusing, but Doc Hudson is the Cars character specifically tied to the Hudson Hornet.