Wondering how to get those certain cars? Just follow the instructions and you should get the cars:
Colin McRae R4 : Beat the X-Games Europe
Dallenbach Special : Beat the Trailblazer World Tour
Ford Escort MKII : Beat all X-Games events
Ford RS200 Evolution : Beat the Rally Cross World Tour
MG Metro 6R4 : Beat all of the X-Games events
Mitsubishi Lancer Evolution X : Beat the X-Games Asia
Mitsubishi Pajero Dakar 1993 : Beat the Raid World Tour
Subaru Impreza WRX STi : Beat the X-Games America
1995 Subaru Impreza WRX STi : Beat the Colin McRae Challenge
Toyota Stadium Truck : Beat the Landrush World Tour