Mack is a supporting character in the Cars franchise. He is a supporting character in Cars, a minor character in Cars 2, and a major character in Cars 3. He is Lightning McQueen's trailer truck. He is voiced by Pixar regular John Ratzenberger.
Mack is responsible for transporting Lightning McQueen to all his races. McQueen exhorts Mack to drive through the night to his tiebreaker race with Chick Hicks and The King in Los Angeles, despite federal DOT regulations which legally grant Mack ten hours daily of much-needed off-duty rest alongside "all those sleeping trucks" at the last truck stop on I-40. Lightning hopes to reach the venue first and to hang out with the Dinoco team. As a result, Mack falls asleep and, distracted by the Delinquent Road Hazards (who attempt to push him off the road to the shoulder), loses Lightning. He is seen on television as he arrives in California and discovers that McQueen is missing.
Later Mack arrives in Radiator Springs after Doc reveals Lightning's location and is both very relieved ("Thank the Manufacturer, you're alive!") and apologetic ("I'm so sorry I lost you, boss. I'll make it up to you..."). Lightning, who is glad to see him, forgives him. Mack takes the reluctant McQueen out of Radiator Springs to compete in the race.
At the final race, he was to act as McQueen's pit crew before the Radiator Springs folks came. During the credits, he watches parodies of other Pixar movies and notes that all of them feature a character played by John Ratzenberger, and amusingly, he is voiced by Ratzenberger as well ("Wait a minute, here. They're just usin' the same actor over and over! What kinda cut-rate production is this?!").
Mack makes a couple minor appearances as part of McQueen's Piston Cup racing team. He also has some slight differences in his design in this film, possibly to take on McQueen's own redesign: while in the original film his cap-shaped wind deflector is white, here it is red. The design of his trailer is also different.
In the sequel, he is briefly seen at the beginning when McQueen comes back to Radiator Springs, where he says one of his only two lines, "Oh, these best friend greetings are getting longer every year." He doesn't accompany him to the World Grand Prix due to being on vacation. At the end he talks with Lizzie and says the other of his only two lines of the movie, "Oh, those two are perfect for each other."
Lightning with Mack outside the Rust-eze sponsor tent.
Mack, exhausted, tries to stop at a truck stop, but McQueen won't let him.
Mack trying very hard to stay awake
Mack put to sleep by the Road Hazards then hustled by them.
"What? Did I forget to wipe my mudflaps?" Mack arrives at the Cali speedway to discover that Lightning's gone.
"You're here! Thank the Manufacturer! You're alive!"
"You are a sight for sore headlights! I'm so sorry I lost you, boss!"
"We gotta get him back out there fast, or we'll be a lap down and we'll never win this race!"
"Wait a minute, here! They're just usin' the same actor over and over! What kinda cut-rate production is this?!"
Mack and McQueen having returned to Radiator Springs at the end of the racing season.
Mack seeing Mater rush to greet McQueen.
"Oh, these best friend greetings! They get longer every year!"
Mack in Cars 2
In the sequel, Mack has the least amount of dialogue out of all of John Ratzenberger's Pixar roles because he only had two lines.