-Purchase the used cars and fix them up. Put them back on the market and you will get more money than you would if you sold a new car. If you want even more money for the old cars, keep them until the next era and they will be worth $60K.
-Buy a used car and choose an "Overall" repair. When completed, the value of your car will be higher than the purchase price and the cost of the repairs. Sell the car, buy another used car and repeat as needed.
-To earn a profit of about $5,500 or more (depending on how far you are in Underground mode), follow these steps. Go to Underground mode and enter the "Customize Ride" menu, then select the "Trade" option and trade your car for a Mazda RX-7. If you already have it as your car, skip this step. Downgrade all of your performance upgrades to stock, then go back to the "Trade" option and trade your car for a Volkswagen Golf GTI. Then, put all of your performance upgrades back onto the Golf GTI and trade your car for the Mazda RX-7. If done correctly, you should gain a profit of at least $5,500. Repeat those steps as many times as desired. In a short time you should have at least $30,000.
-For faster money in the Evolution round, when selling a car enter a higher price for it than the price in the market. You will get more money than the market price.