skills

Best answer as chosen by Asker / Ratings
1. If you mean add new cars,no. But you can change the way some cars modded, if you have the cheat device: action replay max. Now I know this
For a fact because I use ar max to put nitro,different tires and colors
On different cars types like the hot ring racer. I also I up loaded my saves to prove this it can be done.

2. After you beat the test drive mission.