What is the name of the racing championship in Pixar's Cars movies?

The racing championship in Pixar's Cars movies is called the Piston Cup.

The Piston Cup is the main stock-car racing competition in the first Cars film. Lightning McQueen enters the season as a rookie contender and travels toward the championship race, where a three-way tie leads to a decisive final contest. The competition is modeled in broad terms on American stock-car racing rather than on one exact real-world series.

The Piston Cup name also appears in Cars 3, where veteran racer McQueen struggles against a new generation of high-performance competitors. Its branding, sponsors, and tracks help establish the fictional sporting culture of the Cars universe.

The Piston Cup is different from the World Grand Prix in Cars 2. The World Grand Prix is an international event created for the second film, while the Piston Cup is the recurring American stock-car championship connected most closely with McQueen's career.