As far as the drag race guys, looks like some suspension setups can help, but it's mostly in the throttle control. The physics engine seems to like tire spin a bit more than you'd think, so maybe err on that side of things rather than just a clean launch and good weight transfer.
Also, anybody had opponents drive directly into the wall and keep it floored for a smoke show in a drag race? It happened to me like 4 or 5 times last time I played, i understand some variation in AI but WOWIE.