In Pixar's Cars 2, Mater's occupation during the story's opening is tow truck.
Mater remains Radiator Springs' resident tow truck and works at his towing business before becoming involved in the international spy adventure. His friendship with Lightning McQueen leads him to accompany Lightning to the World Grand Prix, where his unusual behavior causes others to mistake him for an undercover agent.
The film turns Mater's ordinary job into part of the comedy. His lack of formal spy training contrasts with his accidental success, while his mechanical knowledge and loyalty repeatedly help the real agents. The story also makes clear that Mater is not pretending to be a professional secret agent at the beginning.
Mater's occupation is sometimes confused with his role later in the film. He becomes a spy by circumstance, but his established job and identity in Radiator Springs are those of a tow truck.