Suggestion:
It depends on where you buy the other car. For example, let's say you owe $15,000 on your Sentra. CarMax offers you $10,000 for it. That means that $5,000 of the loan is still floating out there. If you buy a car at CarMax, you can roll that negative equity into the new car payment. To do this, you have to have good credit and you can only roll so much negative equity into a new payment.
If you don't want to buy a car from CarMax, I'm pretty certain you have to come up with the $5,000 to pay off your loan at the time of sale. The loan company won't issue a title to CarMax until the loan is paid in full, and CarMax won't want the car until the loan is paid in full. So, you either have to sell the car and roll the negative equity into another car from CarMax, or sell it to them and pay the $5,000 out of pocket to close out the loan.
{ 3 comments… read them below or add one }
No.
they wont buy it without title/you cant sell it without title
20. What if I have a lien on my car?
We will need to contact your lien holder during business hours to get a 15-day payoff. To pay off the lien, we will need your lien holder's name and phone number, the name(s) on the account, and your lien holder's account number and social security number. If a previously paid-off lien is listed on the title, you'll need both the title and the lien release from the lien holder before we can purchase your car.
http://www.carmax.com/enus/we-buy-cars/we-buy-cars-faq.html#What-if-I-have-a-lien-on-my-car-