In June, used-vehicle prices hit a 16-year high, making it the best time in years for Americans to sell a car — but a bad time to buy one. Why? New-car sales have been down for several years as consumers held off on buying big-ticket items. Leasing also decreased as many consumers struggled to get credit. Meanwhile, many drivers held onto their own cars longer, decreasing the supply of used cars on the market. The results were striking. Compact cars two to five years old sold for an average of $10,489 in August, compared with $8,798 the year before. However, in recent months used car values have begun to dip again and are expected to keep falling.