In Pixar's Cars, Doc Hudson is revealed to be the retired racer known as the Fabulous Hudson Hornet.
Doc initially serves as Radiator Springs' respected physician and judge. He is also skeptical of Lightning McQueen, whose careless arrival reminds him of the attention-seeking racers he once knew. McQueen eventually discovers that Doc has a remarkable history of his own.
The Fabulous Hudson Hornet was a celebrated fictional racing champion who won three Piston Cups. Doc's career ended after a serious crash and a period of being ignored by the racing world. His experience helps him understand both the dangers of racing and the importance of loyalty.
Doc Hudson is modeled on a real Hudson Hornet, a car associated with early stock-car racing. The character's voice was supplied by Paul Newman, whose performance became one of the film's defining elements.