Most of the cars that compete at the Silver State are far from stock and the race is basically a straight line which favors big displacement, high horsepower cars. I agree with Noreturn an STI or Evo at the ring against a Mustang GT(which is in the same price range) and the Ford loses.

As far as the Cobalt SS and Saturn Ion Redline they need to be supercharged to produce 200hp w/ a 2L engine because the stock 2.4L can only make 170hp. Honda makes an engine w/ 197hp w/ the same displacement, Toyota makes a 1.8L w/ 180hp, Mitsu. made a 1.6L w/ 170hp, BMW 2.3L w/ 190hp and those don't have superchargers to help it make power. Imagine what the Corvette if it made the same power per liter as the Japanese and European engine. 6.1L in the current Z06 would make over 600hp instead it makes 500hp which Ferrari only needs 4.3L to make about the same horsepower. So American engines tend to waste alot to make a little in horsepower. See this clip from Top Gear.