The fictional racing championship sought by Lightning McQueen in Pixar’s Cars is the Piston Cup.
At the beginning of the 2006 film, Lightning is one of three drivers tied for the season-ending Piston Cup race. He wants to win the title outright, but his arrogance and impatience lead to the accident that strands him in Radiator Springs. The championship gives the opening story its immediate sporting goal.
The Piston Cup is a fictional competition inspired by American stock-car racing. Its trophy and races echo the visual language of motorsport without reproducing one real league exactly. Dinoco is the famous sponsor associated with the championship, while Rust-eze sponsors Lightning.
Cars 2 centers on the World Grand Prix instead, an international competition involving Lightning and racers from several countries. That is why World Grand Prix is a plausible but incorrect answer for the original film’s main championship.