Play through Career Mode to unlock these cars.

Unlockable - How to Unlock

Ardent - Earn any medal in the Boxed In event.
Demon - Earn any medal in the Rod Rage event.
Enforcer - Earn any medal in the Swift Justice event.
Guardian - Earn any medal in the Short Stretch event.
Hitman - Earn any medal in the Tommygunner event.
Honcho - Earn any medal in the King of Bling event.
Hookzilla - Earn any medal in the No Parking event.
Kodiak - Earn any medal in the Monster Mash event.
Magnus - Earn any medal in the Heads Up event.
Opulent - Earn any medal in the Laps of Luxury event.
Outlaw - Earn any medal in the Toll 'N' Thunder event.
Phantom - Earn any medal in the Bayside Brawl event.
Rampart - Earn any medal in the Raging Bull event.
Roughneck - Earn any medal in the Trail Breaker event.
Streamline - Earn any medal in the Shore Leave event.
TEC - Earn any medal in the Heads Up event.
Vulcan - Earn any medal in the Catch My Drift event.
Warlord - Earn a Full Auto medal in the Armageddon event.
Wraith - Earn any medal in the Killer Curves event.