Since the car sales have been rising in U.S. for 7 years, of course that the value of used cars we’ve got parked in our garages would dent. There are hundreds and thousands of new cars rolling out of dealerships lots and this means they instantly become used cars. The secondary market is glutted and the pace of depreciation is rapidly accelerating. Your not-that-old car might not be a clunker quite yet, but it's probably a lot closer than you think. The average used car lost 17 percent of its value in the past 12 months, dropping from $18,400 to $15,300. That annual depreciation figure has been increasing steadily, too.