So far the only things I have replaced on my car since it was new: brake pads, brake rotors, tires, shocks (wanted newer ones), and a lug nut or two here and there. The usual wear-n-tear items you would see on the street, just at an accelerated rate. My car had 80 miles new and now has 40,500.

Realistically autocrossing is easier on your car than drag racing. You really are not doing high rpm drops like drag racing. I rev to about 3000-4000 and feather the clutch to go.