Doc Hudson (also known as The Fabulous Hudson Hornet or simply Doc) is the secondary tritagonist in Cars.
Doc is a car of few words but many talents. He not only serves as the town judge, he's also Radiator Springs' resident doctor. Doc is respected and admired by the townsfolk for the way he looks out for their health and tends to their aches and pains. No one knows too much about Doc before he came to town. He keeps his private life private. But if you've got a bad spark plug or a rattle in your engine, his door is always open.