Go to the garage:
Press [Ctrl] + R when in a battle.
When in battle, press [Alt] + [F4] to quit the screen.
Press [Ctrl] + W when "Walkover" appears on the screen.
Extra Extra Money:
Go to the workshop and hold shift+alt and press 5 to get $50,000.
In the middle of a battle press ctrl and f4 and once the battle is done you will have 50,000 credits in your bank. You must win the battle though and you have to be in the same ranking class as your opponent.