The Dinoco 400 is the race where the Piston Cup champion is decided in Pixar's Cars.
The film opens with the three-way tie among Lightning McQueen, Chick Hicks, and The King. Because none of them has secured the season championship, they compete in the Dinoco 400 at the Los Angeles International Speedway. The race is intended to settle the title, but the ending creates an unusual three-car finish.
McQueen's failure to accept help and his mistreatment of his pit crew contribute to his difficult position. After becoming stranded in Radiator Springs, he returns to compete with a different understanding of teamwork and responsibility. His final decision during the race becomes more important than simply claiming the championship.
The Dinoco 400 should not be confused with the Florida 500, which is the major race in Cars 3. Dinoco is also the sponsor that The King hopes to continue representing, making the race name especially significant to the first film's racing world.