NASCAR and Indy were much faster years ago until both have been restricted. If I recall correctly and I think I do, lap speeds of 240 mph were being hit at Daytona and Indy.
NASCAR bodies don’t handle at all above 200mph. IRL does, but drivers start to blackout at 240 on the corners.
That’s what I suspect happened to Paul Dana, Danica’s former teammate. Though IRL wouldn’t talk about it.