I had a similar idea, but slightly different. While playing GTA IV I got the idea, well reminding me of a former idea. I'd love to be able to buy, customize, and park the vehicle where ever I leave it. Whatever condition it was left in is the way it stays (something like Driver Parallel Lines).
I have some great ideas, however Rockstar has me stumped with this lastest installment to the series. Other than graphics and crash physics this game is very empty!