In Pixar's Cars, Lightning McQueen enters the Piston Cup race at the film's climax.
The Piston Cup is the championship competition that drives Lightning's early ambition. At the beginning of the film, he is a rookie contender tied with veteran racers The King and Chick Hicks. A three-way tiebreaker is scheduled after the racers finish level on points.
Lightning's time in Radiator Springs changes how he approaches the final contest. He learns that racing is not only about personal fame and sponsorship, especially after Doc Hudson explains the consequences of being treated as disposable by the racing world. During the finale, Lightning gives up a likely victory to help The King after Chick Hicks causes a crash.
The Piston Cup is fictional, although its presentation draws on American stock-car racing and NASCAR traditions. The Dinoco brand is a sponsor within the film, not the name of the championship itself. That distinction makes “Piston Cup” the specific answer rather than a sponsor or individual race name.