Answer
Lets say that for purposes of estimating that your jeep has a trade in value of $15,000, and you owe $20,000. that means you are
$5,000 "upside down". you will have to come up with the cash to cover this amount, or if you have great credit, the dealership can discount the truck and raise the selling price to cover this amount. you just have to work with the dealer to get it done.