In Pixar's Cars 3, Doc Hudson inspires Lightning McQueen through old training footage.
Doc Hudson was the Fabulous Hudson Hornet, a three-time Piston Cup champion and the former head of Lightning's racing team in the first Cars film. After his racing career ended, he became Radiator Springs' doctor and judge. His history is central to Lightning's understanding of discipline and mentorship.
In Cars 3, Lightning discovers archival footage of Doc's racing days and learns more about Doc's relationship with his own crew chief. The material encourages Lightning to rethink his role and eventually support Cruz Ramirez's racing future.
Doc does not appear as a living participant in Cars 3 because Paul Newman, his original voice actor, died in 2008. The film uses earlier footage and memories to keep Doc's influence present. Strip Weathers, known as The King, is another retired champion, but he is not Lightning's mentor in this storyline.