In Pixar's Cars 2, which car becomes an undercover spy working with Mater?

In Pixar's Cars 2, Finn McMissile is the undercover spy who works with Mater.

Finn McMissile is a British secret agent who investigates a conspiracy surrounding the World Grand Prix. He meets Mater after mistaking the tow truck for an American agent, and the misunderstanding draws Mater into the film's espionage plot.

Finn is designed as a classic British spy car, with weapons, gadgets, and a refined manner. He is voiced by Michael Caine, whose performance gives the character a deliberate connection to traditional spy-film heroes. Holley Shiftwell later joins Finn and Mater in the investigation.

Finn is sometimes confused with Professor Zündapp, the German weapons expert allied with the villains, or Miles Axlerod, the event organizer at the center of the conspiracy. Finn is the investigator opposing them.