Need For Speed Undercover Cheats for Wii
The following cars become available options by downloading the Challenge Series and completing the corresponding task.
Unlock Dominator Corvette Z06:
Dominate over 30 Challenge Series Events.
Unlock Battle Machine RX-7:
Win the first 30 Challenge Series Events.
Unlock Speed Machine 911GT2:
Win ALL 60 Challenge Series Events.
When you're in takedown mode follow behind your opponent in the same lane and every now and then the other car will slam on it's brakes and you can slam right into him and deal a lot of damage. Hope this helped