Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Pay off car or use money for down payment
Break the transactions into parts. Go to your bank or credit union and get a loan commitment. When applying for loan get the maximum amount they will let you borrow assuming that you will no longer own the first car. Take the car to a dealer and get a written estimate for selling the car. Pick one that gives you an estimate that is good for a week or ten days. You now know a data point for the trade-in value. Finally go to the dealer where you will buy the replacement car. Negotiate the price, tell them you don't need financing and you will not be trading in the car. Get all you can regarding rebates and other special incentives. Once you have a solid in writing commitment, then ask about financing and trade in. If they beat the numbers you have regarding interest rate and trade-in value accept those parts of the deal. But don't let them change anything else. If you keep the bank financing the dealer will usually give you a couple of days to get a check.  If you decide to ell the car to the first dealer do so as soon as you pick up the replacement car. If you try to start with the dealer you are buying the car from they will keep adjusting the rate, length of loan, trade-in value, and price until you have no idea if you are getting a good deal.