Which fictional racing league is featured in Pixar's Cars?

The fictional racing league featured in Pixar's Cars is the Piston Cup.

Lightning McQueen is a rookie competitor in the Piston Cup season, and the film begins with him traveling toward the championship race in California. The league provides the competitive framework for the plot while also giving Pixar a way to parody the visual language of stock-car racing, including sponsors, pit crews, commentators, and racing celebrities.

The Piston Cup is not a real-world racing championship. Its name and presentation evoke NASCAR, but the characters, standings, sponsors, and races belong to Pixar's fictional universe. Dinoco is one of the best-known fictional sponsors associated with the competition.

The name is also used in later Cars stories. Cars 3 continues Lightning's career in the Piston Cup world, while Cars 2 shifts much of its attention to the international World Grand Prix.