Which singer-songwriter wrote the main theme for Pixar's Cars?

Randy Newman wrote the main theme for Pixar's Cars.

Newman composed the film's original score and wrote several songs for its soundtrack. The main theme, commonly identified with the film's instrumental score, helps establish the movie's mixture of open-road adventure, comedy and small-town nostalgia. His music gives Radiator Springs a warm, reflective identity that contrasts with the speed and noise of professional racing.

Newman had a long creative relationship with Pixar before Cars. He wrote the score and songs for Toy Story, including the Oscar-winning song “You've Got a Friend in Me,” and also worked on A Bug's Life and Toy Story 2. His recurring collaboration with Pixar made him one of the studio's most recognizable film composers.

Cars also features songs by other artists, including “Life Is a Highway” performed by Rascal Flatts. That song is a soundtrack track rather than the composer of the film's main musical score, a distinction that often causes confusion.