Collect the indicated number of points in Championship mode to unlock the bonus car:

Bently Hunaucieres 545 points
Audi TT 15 points
Subaru Impreza WRX 275 points
Mazda RX7 335 points
AC Aceca 400 points
Ford mustang GT 30 points
Plymouth Prowler 50 points
Celica GT4 75 points
Dodge Viper 105 points
Lotus 34CR 140 points
Mitsubishi GTO 180 points
AC Superblower 225 points
TVR Cerbera Speed 12 470 points