What is the name of the retired racing champion in Pixar's Cars?

The retired racing champion in Pixar's Cars is Doc Hudson.

Doc is a 1951 Hudson Hornet who lives in Radiator Springs and initially hides his past from Lightning McQueen. He served as the town's doctor and judge, but he had once been a celebrated race car known as the Fabulous Hudson Hornet.

Doc's racing career ended after a crash and a long recovery. When he returned to competition, the racing world had moved on, and the press treated him as obsolete. He consequently left racing and settled in Radiator Springs. His experience allows him to recognize both McQueen's talent and his lack of maturity.

Doc Hudson was voiced by Paul Newman, a lifelong auto-racing enthusiast and accomplished driver. The character is based partly on the real Hudson Hornet, a model that was highly successful in early-1950s stock-car racing. Doc's historical identity is revealed gradually in the first film rather than stated at the beginning.