It is possible to trade in a vehicle that still has an open loan. To determine whether or not doing so benefits you financially, check your vehicle's value and compare it to the car's remaining pay-off amount. If you owe more than the vehicle's loan amount, you may have to carry over money from your old car loan into your new one. Vehicle's Value Get an idea of how much your car is worth before bringing it to a dealer for a trade-in appraisal. While Internet appraisal websites differ in value estimates, you can determine an average trade-in...