Start a new game and save it, do the transfer of $100,000 to give you $110,000 and then by any car you want. A good are for starters if available from the car tuning icon on the world map, click it. Go to HPAmotoersports and click the car icon in the bottom right hand corner and you'll be presented with a supped up VW Golf with over 500BHP. Buy it for $31,870, go back to you garage and save. There is no point adding any tuning items to the car as they wont transfer! You can buy as many other cars too but remember to save your garage.
Then resest you PS2 and swop over the Mmemoury cards so that you start a new game again and repeat the step for transfering the cash. Once you have the $110,000 put the first memoury card in slot 2, go to HOME and select trade. Now you can buythe HPA Golf for $27,089 and using whats left sup it up some more. With this car you can win a lot of races (even without adding to it - 500BHP is a lot of power for very little cash). Have fun