Mack is Lightning McQueen's race-team transporter in Pixar's Cars (2006).
Mack is a large red truck who carries McQueen and his equipment between races. He is loyal and hardworking, but his exhaustion contributes to the opening situation: while traveling overnight toward the Piston Cup finale, he briefly falls asleep and McQueen is separated from the convoy. That separation leads directly to the Radiator Springs story.
John Ratzenberger voiced Mack in English. Ratzenberger has appeared in every Pixar feature film released through the period when Cars was made, continuing the studio tradition of recurring voice cameos. Mack's design also helps establish the contrast between the fast, commercial racing world and the quieter community McQueen later discovers.
Mack is not the same character as Sarge, the military jeep, or Guido, Luigi's small Italian forklift assistant. Red is the town's fire truck. Those vehicles are all associated with Radiator Springs, while Mack belongs to McQueen's racing entourage.