In Pixar's Cars 2, the British spy car who partners with Mater on the international mission is Finn McMissile.
Finn is an experienced intelligence agent who investigates a conspiracy surrounding the World Grand Prix. He initially mistakes Mater for an American agent after seeing him involved in a secret exchange. Mater's accidental involvement then develops into a genuine partnership as the two uncover a plot connected to the race and its broadcast fuel.
Finn is designed as a classic British espionage car, with gadgets, disguises, and a sophisticated manner. His role contrasts with Mater, whose improvised actions and comic misunderstandings repeatedly frustrate conventional spy work. Their partnership is central to Cars 2, which shifts the franchise from Radiator Springs toward an international action-adventure story.
Michael Caine provides Finn's voice in the English-language film. Holley Shiftwell is another British intelligence car and an important ally, but she is not the character who is paired with Mater as his principal field partner.