Cars 2 introduced Mater’s spy identity as an accidental secret agent.
In Cars 2, Mater travels with Lightning McQueen to the World Grand Prix. After a misunderstanding involving British agents Finn McMissile and Holley Shiftwell, Mater is treated as an undercover operative. His ordinary behavior, improvisation, and unusual observations repeatedly help the agents uncover the real threat.
The film shifts the franchise toward international espionage while retaining the friendship between Mater and Lightning. Its locations include Tokyo, Porto Corso, and London, giving the story a much broader setting than the original film’s Radiator Springs-centered plot.
Mater appears in the first Cars film as Lightning’s tow-truck friend, but he does not have a spy role there. Cars 3 returns to a more racing-focused story and centers on Lightning’s changing career. Planes is a separate DisneyToon Studios spin-off set in the same broad world, not a Pixar Cars movie.