Thanks for all the input guys and definately there are some great points that have been brought out.
I talked to a friend of mine that has been in the car business for a long time and he basically said it's not a bad deal but........ He says in order to come out at the end of 39 months with the payment being the same then you would pretty much have to finance it for 48 more months. 48 and 39 makes it 87 months and if I were going to pay for a car that long I will just buy it and finance it for 84 months. Which I usually finance for 72.
As Ben says the deal they are trying to sell me on has the gap already built in. I do also drive a lot of miles and would probably put more than 15K miles a year on whatever I buy.
After reading all the replies here and talking to my friend, I aint going to do it.
Thanks