Doc Hudson was a three-time Piston Cup champion before becoming Radiator Springs' doctor.
In Cars, Doc's past is revealed through his old racing identity, the Fabulous Hudson Hornet. He won the Piston Cup in 1951, 1952, and 1953, but a serious crash ended his career and left him bitter about how quickly the racing world moved on.
After leaving professional racing, Doc settled in Radiator Springs and became the town's doctor and judge. He initially resents Lightning McQueen because the young racer reminds him of the fame and ambition he once had. Over time, Doc becomes a mentor who teaches Lightning about patience, community, and racing technique.
The character is modeled on the real Hudson Hornet, a car that had notable success in stock-car racing during the early 1950s. Doc's history is therefore both a fictional biography and an affectionate reference to American motorsport.