NASCAR inspired the fictional Piston Cup in Pixar's Cars.
The Piston Cup is the championship competition followed by Lightning McQueen, Chick Hicks, and veteran racer The King. Its oval-track races, stock-car designs, sponsor-heavy liveries, pit crews, and season-long points structure reflect the visual and sporting traditions of American stock-car racing, especially NASCAR.
The movie does not use NASCAR as the name of its fictional championship. Instead, Pixar created the Piston Cup and its own racing history so the story could build a self-contained world of talking vehicles. The King is based on the real Plymouth Superbird-era stock cars, while McQueen's design combines several stock-car influences.
NASCAR stands for the National Association for Stock Car Auto Racing. The real organization was founded in 1948 by Bill France Sr. A common mix-up is calling the Piston Cup the Daytona 500; the Daytona 500 is a specific NASCAR race, whereas the Piston Cup is Cars' fictional championship.