I don't know if anyone's written a game like this before in Flash, but here's a very early demo of a Pole Position/Super Hang On-style engine:

http://ant.simianzombie.com/Road.html (5KB)

I've only been working on it for a couple of hours, which is why it's so ropey at the moment.

Cursor keys control horizontal movement; Z is accelerate.

What do you think? Also, I'd appreciate it if you'd let me know how it performs on your hardware.