Should I roll negative equity into a new car loan?

It's possible but costly, since you'll pay interest on debt from your old car and start the new loan even further upside down. Alternatives include waiting and paying down the old loan, paying the difference in cash, choosing a less expensive vehicle or making a larger down payment. If you do roll it over, keep the term as short as you can afford and consider GAP coverage. Make sure the amount appears clearly on the contract.