I think Live4speed's avatar is trying to be a WWE RAW Diva. If that's Carmella, may I wish her luck because she's pretty sexy.
Anyhow, there have been games that offered you loans for you to do whatever. A prime example is when I played "Sim City" on the Super NES. The only way to access loans is to build your city up to 10,000 people (which would mean a "City" designation). When you are asked about building a bank in your city, you are able to take out a $10,000 loan. This was perfect in building a $5,000 Seaport, a $5,000 Nuclear Power Plant, or a $10,000 Airport (in the game, of course. Don't think you can buy out an airport with $10K). If this applied to GT4, you'd have a little more pocket change for tuning up. The weirdest case of loans was in the Bullfrog PC game "Theme Hospital." In later stages, you can take out a $5,000 loan to help pay for hospital costs, building new rooms, purchasing land and countless other stuff. But it's tricky at times. The good thing is that you can pay off the loan whenever you have enough money left to pay the bank back.
Whatever financial plans will be in GT4, take advantage of them when you have money and a good car and plenty of races under your belt. Or imagine leasing a car and having to pay seperate payments every 5 or 10 days! I might want to talk about this issue elsewhere in the future.