Enter the Ultra Racing Cars contest and finish in first place. You will win a Lamborghini Murcielago. Then, go to your garage and sell it for $161,500. You can repeat this as many times as desired.

Buy the Corvette for $45,000 then sell it for $45,500.

At the start of a new career (evolution), do the Saleen Challange and win a Hummer H2. When you get the Hummer, sell it and you will get $67,500. Do the Saleen Challenge again. Continue doing this until you have as much money as desired.