Cars introduced Mater before his later starring role in Cars 2.
Mater is a rusty tow truck from Radiator Springs and one of Lightning McQueen's closest friends. In the first Cars film, he helps McQueen understand the town's community and provides much of the story's comic energy. His friendship with McQueen continues into Cars 2, where the plot gives him a much larger role.
Cars 2 expands Mater's character by placing him at the center of an international spy adventure. His mistaken identity leads agents Finn McMissile and Holley Shiftwell to treat him as an undercover operative. The sequel therefore changes the scale of Mater's story without changing his loyalty or distinctive personality.
Mater was voiced by Larry the Cable Guy in the Cars films. He is sometimes confused with other tow vehicles from Pixar-related productions, but Mater is specifically the character who lives in Radiator Springs.