There's a credit forum (creditboards.com) that has an automotive financing section. One of the moderators, Marv is excellent at answering questions like this. He's worked, or still works at a dealership. I'm pretty sure he either owned, or managed one. And he is very straight forward, objective and really has helped me out in the past with some honest advice (believe it or not).
At any right, I once asked a related question in the forum and got some very interesting advice. Mainly, it was recommended that instead of leasing, I finance and then trade every couple of years or so.
Now obviously, you have to come to terms with paying for the upside-down on your loan, and a new down-payment on a new vehicle. If the financial flexibility is there, the trade-in vehicle miles are low and the vehicle is in great shape...you can do this. It'll just cost you more than you probably want to spend out-of-pocket.
I decided to take this approach, but I added a little twist to it to help me out down the road. I bought my T4R in June '04. I will now send 2 full payments next month – one of them 2 weeks prior to my due date, and the other at it's normal due date. The next month, I will continue to pay 1 payment as normal, but I will send an addition $50-$100 every month (as long as I can do it).
Essentially, I will be paying 1 month ahead of schedule and then continue to chip away at the principal. This way, when I am ready to trade in my financed car in 2 years, my upside-down will be much more manageable. This will help keep my out-of-pocket cost to a reasonable number come 2006 when I go back for a new 4Runner. I REALLY want that V8 now

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