Ended up having to do almost everything manually, except for some reason the rear wheel of the closest white car tracks fine. No idea why.

I was going to try another shot but using tracking markers like ping pong balls but my problem is, how do u remove objects like that from your scene once you've run it through live? I have after effects 6.5 and Photoshop cs2, do either of those allow accurate "painting out" of markers in a shot?

Thanks for all your help

Simon