So to me stock car means what you would buy “off the shelf” which I’m pretty sure was the original intent. It was a normally stocked car.Of course it’s the same car, it’s stock car racing. There are modifications allowed, but there are limits, and every team can them. So basically everyone is driving a Chevy Malibu with a$50k engine that produces 600 hp and a top speed of 200 mph. Theoretically this would show who the best drivers are, but b/c all they do is circles, it really only shows who has the best pit crew.