In a world centered by anthropomorphic means of talk, the Piston Cup season's final race ends in a three-way tie to secure first place mid-term retired veteran Strip "The King" Weathers, regular runner-up Chick Hicks and fast-paced rookie Lightning McQueen; The tiebreaker race is scheduled to take place a week later at the Los Angeles International Highway. McQueen is desperate to win the race, not only being the first rookie to win the Piston Cup, but also because it will allow him to leave the improper sponsorship of Rust-Eze, an ointment company bumper, and took the place of The King on the prestigious and lucrative Dinoco team. However, he struggled to work with others due to his selfishness, which caused him to fire three captains and cause his crew members to quit their jobs after the race. Eager to get to California as soon as possible, he pushed his big rig, Mack, through the night. While McQueen was sleeping, Mack nodded and was startled awake, causing McQueen to fall behind the trailer and fall onto the street. McQueen wakes up in the middle of traffic and rushes off the highway to find Mack, but instead heads to the dingy desert town of Radiator Springs, where he accidentally ruined the main road's pavement.
The next day, McQueen was ordered by the town judge and medical doctor, Doc Hudson, to leave town immediately, but the local lawyer, Sally, asked McQueen to be assigned to serve instead. agree to fix the path, and Doc reluctantly agrees. Still in a hurry to leave town, McQueen paced the street sketchily, and was ordered to start over. During this time, he begins to warm up with the town, and befriend some of its inhabitants. He knew that Radiator Springs was once a famous stop along US Highway 66 until it was skipped during the construction of Interstate 40 and was mostly forgotten, and that Doc was Fabulous Hudson Hornet, three-time Piston Cup champion whose career ended in a devastating battle crash in 1954. He bonded with Sally, who found happiness when she gave up a hasty life in Los Angeles to live in Radiator Springs, and now dreams of bringing the town back to the map. McQueen finished fixing the road, revitalizing the town's inhabitants, and decided to spend an extra day in Radiator Springs with his new friends, but his time was cut short when Mack and The media landed in town. McQueen was reluctant to leave to get to California to catch up with the race while Sally expressed her disappointment to Doc when he discovered that he was responsible for the media about McQueen's whereabouts.
At the race, McQueen raced distracted and soon fell to last place. He is then surprised to discover that Doc, a heart-changing, has taken over the position of captain of him and some of his other friends from Radiator Springs are helping out in the pit. Inspired and remembering tricks he learned from Doc and his friends, McQueen has come to the fore. In the final round, Chick passed and put The King in a dangerous accident. Recalling Doc's fate, McQueen stopped just before the finish line, handed the victory to Chick, and turned to push The King over the finish line. As a result, the angry crowd and the media condemned Chick's victory but praised McQueen's athletic spirit. McQueen was offered a sponsorship by Dinoco, but declined and insisted on staying with Rust-Eze out of loyalty to their previous support. Back in Radiator Springs, McQueen reunites with Sally and announces that he will set up his racing headquarters there, bringing Radiator Springs back to the map.
In a post-credits scene, Minny and Van, a couple trying to find Federal Route, get lost in the desert.