can i do this????

can i do this????

Hello can someone please tell me if there is an easier way too unlock the bonus cars such as the lexus is300, the Lotus europea, and the road runner, please tell me there is an easier way to unlock those cars without going online, my sister bought an xbox 360 from her friend and she couldn't find the internet cord, like can I unlock those cars from certain challenge series races or something, we are working on the reward cards and the bmw m3 gtr reward card is kind of hard to get when I need 33 cars unlocked, pleas somebody answer me as soon as possible?????