In Pixar's Cars, Lightning McQueen's trailer is named Mack. Mack is a red truck who transports the race car between events and serves as his loyal support vehicle.
Mack appears early in the film while carrying Lightning toward the Piston Cup finale. When Lightning is separated from Mack after a chaotic incident on the highway, he ends up in Radiator Springs. That separation is the event that launches the main story.
The character's name can be confused with the names of other Cars vehicles. Tex is a wealthy sponsor associated with the Dinoco team, Sarge is a military-style Jeep, and Guido is Luigi's assistant at the tire shop. None of those characters is Lightning's traveling trailer.
Mack is also notable because his truck design reflects the practical relationship between a professional racer and the support equipment needed for long-distance competition. He is a character in his own right, but his main job in the first film is moving Lightning and his racing gear.