Start a game with "-cheater -invince" command line parameter. Then, while playing the game, press [Alt] + [Ctrl] + [F7] before hitting a vehicle or person.
Infinite ammunition and weapons
Start a game with "-cheater -infinite" command line parameter. Then, while playing the game, press [Alt] + [Ctrl] + [F7] before hitting a vehicle or person.
No cars
Start a game with "-cheater -nocar" command line parameter. Then, while playing the game, press [Alt] + [Ctrl] + [F7] before hitting a vehicle or person.