In Pixar's Cars 3, Cruz Ramirez becomes the new Piston Cup racer after taking Lightning McQueen’s place.
Cruz begins as Lightning’s trainer at the Rust-eze Racing Center. Although she is skilled at analyzing data and designing exercises, she has long been treated as a technician rather than a competitor.
During the Florida 500, Lightning realizes that Cruz has the speed and racing ability to challenge Jackson Storm. He gives her his chance to compete, and she wins the race while driving with Lightning’s number 95. The ending establishes Cruz as a new Piston Cup racer and Lightning as her mentor.
Cruz’s victory does not mean she had already been Lightning’s replacement at the start. Her professional role initially involves training and performance analysis, and her move into racing happens through the film’s final competition.