Mack

Mack is a character in Cars and its sequel. He is voiced by John Ratzenberger.

Cars
Mack is responsible for transporting Lightning McQueen to all his races. After Lightning pushes him to drive all night to California, Mack falls asleep and ends up losing McQeen. He is seen on television as he arrives in California and discovers that Lightning is missing. He is again see at the final race as a spectator. During the credits, he watches the parodies of the 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.

"Endless days on the road and sleepless nights criss-crossing the country... For some this life would quickly grow old. But not Mack. No sir. Mack knows how important his role is. He's driving Lightning McQueen, the world's fastest racecar. He's part of a team, and everybody knows there's no I in team, just like there's no I in Mack."

Cars 2
Mack makes a few minor appearances as part of Lightning's racing team.

Mack is Lightning McQueen’s trusted long-haul driver, crisscrossing the country from race to race, always with a smile on his grill. After dropping Lightning off in Radiator Springs with his fourth Piston Cup championship trophy, Mack sets off with the rest of the pit crew for a well-deserved vacation. Who knew that Lightning would end up jetting off to a race around the globe in the World Grand Prix?

In the film he is briefly seen at the begining when Lighning goes back to Radiator Springs, where he says one of his only 2 lines. 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 2 lines of the movie.

The two lines that he had were: "Oh, his best friend greetings, they get longer every year," and: "Oh, those 2 are perfect for each other."

Trivia

 * Mack is a 1980s-era Mack Super-Liner truck.
 * When Mack watches the Cars-parodies of previous Pixar movies, he think that the car who does the voices of Hamm, P.T. Flea, and the Abominable Snowman as cars is one great actor until he realized they used the same voice actor in all movies. He wonders "what kind of a cut-rate production is this?," which is a reference to John Ratzenberger (who portrays Mack) portraying at least one character in every Pixar movie.
 * In Cars 2, he has the least amount of dialogue of all of John Ratzenberger's roles, only having two lines.