Indycars have raced regularly at Datoyna, I believe they were getting near 240, but they were having repeated accidents even in warmups with no other cars on the track. They proceded to require more drag. If you look at the cross-section of an Indy or F1 car, you'll notice the huge square blocks at either end of them. The tires on those cars will never allow the smooth air flow to hit 275 on a straight and still hold in a corner.
The olds demonstrated more than the Quad4 engine... it also demonstrated airfoil design on an automobile. Anyone can make 800 horsepower, keeping it on the track is an entirely different issue.
BTW... there was a test done some time ago when they time trialed the Porsche Group B against a NASCAR racer at Daytona. Was a very good read, and they were pretty evenly matched.
MiniD
