It's running at 240fps now with the throttle off
That's 0-60 in around 2 seconds, around the same as a real F1 car!
It's the throttle code causing the slowdowns.
It's now just a case of getting the correct throttle settings.
DOUBLEBUF and TRIPLEBUF settings also causing significant slowdowns.
EDIT
Now we're hitting 290fps with IPU, HWSURFACE with throttle off!