During play, hold Ctrl + Alt + Shift + F7 until a prompt appears. Now enter the following codes (note - some of these will disable scoring):

/dizzy     Spinning sky
/fuzz      Toggle police radar
/ufo       Airplanes are UFOs
/swap      Trains are airplanes
/slide     Traffic cars slide
/puck      Player's car slides
/grav      Low gravity
/big       Large people
/tiny      Small people
/damage    Damage mode on
/nodamage  No damage mode
/talkfast  Fast commentary
/talkslow  Slow commentary
/smoke     Smoking tires
/nosmoke   No smoking tires
/postal    Use horn to shoot mailboxes

Disable the Unnerving Timer:
Press F2 to pause the game Then press 'Q' twice and the event will continue with the timer disabled! This is really handy in the crash course and in blitz races.

        Hints:

To Unlock Cars:

New Mini Cooper:
Place 1st, 2nd or 3rd in 5 London Blitz races.

New Beetle Dune:
Place 1st, 2nd or 3rd in 5 San Francisco Circuit races.

New Beetle RSI:
Beat the San Francisco Crash Course.

Audi TT:
Place 1st, 2nd or 3rd in 6 San Francisco Checkpoint races.

Aston Martin DB7 Vantage:
Beat the London Crash Course.

Panoz GTR-1:
Place 1st, 2nd or 3rd in 6 London Checkpoint races.

American Lafrance Fire Truck:
Place 1st, 2nd or 3rd in 5 San Francisco Blitz races.

N.B.:
In the professional mode, you have to finish always 1st.

The Hummer:
Beat the San Francisco crash course.
 

On My Good Side:
To get the camera to pan around quickly while driving in reverse: Right before you wish to throw it in reverse (while in the 3rd person view) press F2 to pause the game. Even though the game is paused, you are still able to change gears. Throw it in reverse and the camera will turn around, press F2 again to unpause and be on your way!