Cheats
If you delete the game 4 times then change you username and password to something different then go to game centre and change the name then delete the game again ( by me saying delete the game I mean delete it all together) if that does not work delete it another time and this will give you all achievements and all things in the game and this works on some other games as well and also you don't have to be jail broken and the first 3 times you delete the game it will delete the game all together but on the last couple I promise it will turn your game in to the best.
F1 Vehicle Parts
You can unlock the Formula 1 vehicle parts (such as the engine and rear spoiler) by accessing the Stig Trail, building a car, viewing the Stig's lap and then racing him. As long as you get a Gold medal, you'll receive the parts.
Fastest Car (requires DLC)
To get the fastest car, unlock the supercar and buy the super powerrr engine. Equip the sidewinders (sides), jet engine (top), and rockets (back).
