Lightning McQueen, a legendary race car, is enjoying his time as a top racer, when a new generation of high-speed racers begins to outpace him. Among them is Jackson Storm, an advanced and arrogant model who represents the newest advancements in technology. Lightning, now considered an old model, faces continuous defeat, which culminates in a devastating crash that signals the potential end of his career. He is determined not to be forced into retirement and to prove he still has the speed and heart to win, Lightning embarks on a journey to get back in the game, seeking the help of his old friends at Radiator Springs.

Undergoing a rigorous training program with the help of an enthusiastic young race technician, Cruz Ramirez, Lightning works to adapt to the modern ways of racing, which focus on simulators and analytics. However, his old-school, hands-on approach clashes with these new methods, leading to frustrations and setbacks. In his quest to remain a champion, Lightning finds himself questioning not just his abilities, but also the very core of what it means to be a racer. Meanwhile, his growing bond with Cruz presents an unexpected opportunity to discover that winning can come in different forms, and sometimes, a mentor can become the mentee.