What is the name of the fictional racing competition in Pixar's Cars?

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

The Piston Cup is the main stock-car championship in the first Cars film. Lightning McQueen competes for the title alongside veteran champion Strip Weathers, better known as The King, and rival Chick Hicks.

The competition is modeled on the structure and visual language of American stock-car racing, especially NASCAR. Its name also evokes the Piston Cup trophy awarded in the real-world film The Great Race and the mechanical imagery associated with cars.

Cars 2 shifts attention to the World Grand Prix, an international event involving races in Japan, Italy, and England. That different competition is a common mix-up, but the Piston Cup remains the defining championship of the original film and Lightning's early career.