First off, you need to finish the story mode to get the Super Car, otherwise your chances are slim!
You need Gold medal in every tournament. You don't need gold in every stage of the tournament, just overall (about 60% gold medals, 40% silver).
- if you don't get gold in a stage, you can select restart right after the leaderboards screen of that stage. it tells you that you lose all progress if you restart, but you don't, you keep everything, including the money you earned in your race. You restart directly at that stage you just drove, losing no progress!!! This means, you can try, till you get gold or silver (however many points you still need).
- for elimination I used the Super Car, fully upgraded.
- for races and endurance I used the Hotrod! The Hotrod is half as big and you don't get stuck so often, which makes it easier!
- if you get stuck, remember to press Back on your controller, resetting your position!
- For Endurance, remember to ram stuff all the time (best by driving along the outer lines!) and use your weapons non-stop, every little thing you hit earns you valuable time!
If you struggle, try and memorize the best road to take. the best roads can save you important seconds!
At the third tournament I had everything completely upgraded.