Cars 3 features retired racer Doc Hudson as Lightning McQueen's mentor through flashbacks.
Doc Hudson died before the events of Cars 3, but the film revisits his racing career and his relationship with McQueen through archival footage, memories, and dialogue. These scenes help McQueen understand how Doc dealt with a career-ending setback and eventually found a new role as a mentor.
Doc was introduced in the first Cars as the Hudson Hornet who served as Radiator Springs' doctor and McQueen's reluctant teacher. He had once been a celebrated racer, but a serious crash ended his Piston Cup career and left him bitter about the sport.
The character is voiced in Cars 3 through previously recorded material by Paul Newman, who died in 2008. Newman's earlier performance as Doc remains central to the character's history in the franchise.