Drive all cars:

 Drive a few seconds with the VW Beatle in Tour mode in San Francisco.
 End the game and open the file player1.sav with a text editor and look
 for

 vpbug

 Put a p directly behind it (vpbugp). Save and restart the game.

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 Unlock the cars with:

 American Lafrance Fire Truck   Place 1st, 2nd or 3rd in 5 San Francisco
                                Blitz races
 Aston Martin DB7 Vantage       Beat the London Crash Course
 Audi TT                        Place 1st, 2nd or 3rd in 6 San Francisco
                                Checkpoint races
 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
 Panoz GTR-1                    Place 1st, 2nd or 3rd in 6 London Checkpoint
                                races
 N.B.                           In the professional mode, you have to finish
                                always 1st

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 While playing a game, press [Y] and type

 damagefree     No damage
 midtowncars    All cars