In Pixar's Cars 3, which racer becomes the 2017 Piston Cup champion?

In Pixar's Cars 3, Cruz Ramirez becomes the 2017 Piston Cup champion.

Cruz starts the film as Lightning McQueen's trainer, not as an established top-level racer. During the Florida 500, Lightning realizes that Cruz has the skill and determination to challenge Jackson Storm. He gives her his racing position, allowing her to enter the competition in his place.

Cruz wins the race after an intense battle with Storm. The victory completes her transition from technical trainer to professional competitor and gives the film its generational handoff. Lightning does not disappear from racing; he adopts a new role as Cruz's mentor and continues racing in a different capacity.

The year 2017 refers to the film's championship season, not the year the movie was released in all markets. Cars 3 was released in 2017, and its final race is the fictional Florida 500. Jackson Storm remains Cruz's principal on-track rival in that event, while Lightning's decision makes the result possible.