Go to the options menu and enter the following codes at the bonus
screen:
     Note:  Only  a  few codes will work in all games. Some codes vary
from game to game, depending on your bonus number.

     To     get     cheat     codes     register    your    game    at
http://www.codemasters.com/register.  They  will  send you two cheats.
You first need to sort out code "m" at the website first.

Enter the codes at the bonus screen. 
Unlock all cars: Enter XKIMCF, LEZEJD, or SAFREA
Unlock all tracks: Enter QTRIKX, TMYTKO, NIQHLT, NPXOOY, MPXOOY, or HZCGYP
All championships: Enter QTRRDJ
All challenges: Enter LSDUXH 
Pro Race Driver tracks: Enter LQJFFA
Realistic handling: Enter SIM, VIBAKH or LJLZEL
Enhanced damage: Enter DAMAGE
No damage: Enter IHHBIV, OATRYU, or MMMFJL
View credits: Enter CREDITS or XQIXCJ