Well, it looks like you are going to find out..........
BAR are going to run one of their 007 cars at Bonneville this year. As I understand it, they will run a car to full FIA spec, but trimmed out to see just what the top speed could be. That means the car will have wings, mirrors etc. I read that they intend to remove some of the winglets etc. as downforce is not the priority.
Apart from sticking a parachute on the back - that's it............
Estimates of the top speed seem to be around 250mph.
Let's wait and see.