what system requirements are you expecting for it?
It's running at between 60fps and 30fps with 8 cars, hi-res textures and anisotropic filtering on my P4 2.4 (with 6600GT), but 8 cars is a bit over the top - 4 cars would probably be enough in most cases.
I also need to try out some complex tracks and see how it reacts to those.
Can I ask, was it my advice you followed?
I just checked my emails and you did send me some info, thanks. I made up a pretty simple system of waypoints in 3 lanes around the track. The cars have the option of following each lane, then they react by accelerating or braking dep. upon the distance and angle to the next checkpoint.
They have 4 states - accel, coast, brake or handbrake dep. upon the situation they are in.
The tricky bit was getting a balance between these states, so the car is fast but not too fast to stay on the track.