What fictional racing cup is contested in Pixar's Cars?

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

The Piston Cup season drives the opening and closing portions of the film. Lightning McQueen, Chick Hicks, and The King are tied before the final race, creating the three-way contest that sends McQueen onto the road toward California.

The name is a playful reference to the piston engines associated with many racing cars. Within the Cars universe, however, it is a major professional championship with sponsors, television coverage, pit crews, and a large fan following.

The Piston Cup is not the same thing as a real-world NASCAR championship, although the film borrows visual and structural ideas from stock-car racing. Cars 2 shifts the focus to the World Grand Prix, while Cars 3 returns to the Piston Cup setting.