Code        Effect  
machthree   600 km/h super car   
impact      Unlimited ammo in death match mode   
clementine  Free choice in starting league   
overkill    Enable weapon mode in championship mode  
mccoy       Animated switches in menus   
likepamela  Tuning phase 5 for all systems   
liselotte   All additional systems at 99   
nalice      All cars  
alloff      Disable cheats   
     

Thanks to Revolution reader Brokeneck!