To make this cheat work you need at least 80,000 credits in the bank to begin with. When you've got it, buy a VW jetta GLX VR6. Select it as your car and go to the engine upgrades section.
Next, you'll need to buy every level of every upgrade possible (except the engine itself). Once you've done this, buy the upgraded engine, then reinstall the stock engine.
If you've done everything correctly you should now be able to sell the upgraded engine for about 43,000 credits. Keep doing it as many times as you want and get as much money as you want
Added by: nicknak14 Aug 28th 2006, ID#6273