Im in the car business. the deals on the radio for early turn in vary from car company to car company, not dealer to dealer, just depends on your maturity date. you can roll the difference into a new car, or pay the difference off. as for blowing off the excess mileage charges if you keep the car, its not a good idea. if the bank decides to be hard about it, the will collect half, then report that you only paid half to the credit reports, its still a negative on your bureau. If you still have 4,000 miles to go wait to see when your lease would qualify for a pull ahead program then get a new car, at that point, you wouldnt have to pay off your remaining payments. If pull ahead goes away, and you still want a new car, then roll your remaining pmnts into a new car. What make vehicle are you driving??
BTW. you will prolly have to stay with the current brand your driving. Chrysler, Ford, GM, etc to take advantage of the pull ahead program