Consult more than one source to make sure you have a solid sense what your soon-to-be-former car is worth. Edmunds.com, a trusted resource for auto info (the company has been around for 50 years) and the Kelley Blue Book (kbb.com) let you easily see the approximate value. For a more specific number, visit a CarMax near you (there are 150 nationwide). At no cost, this used-car retailer will check out the vehicle and give you a hard offer on a trade-in. Then you’ll be ready to get tough if a dealer lowballs you on the worth of your car. While you’re doing trade-in research, investigate cash-back offers on the vehicle you’re planning to purchase. At edmunds.com you can input the precise make, model, and details of the new car and learn what rebates are available.