Dealers buying at auction saw used-vehicle depreciation accelerate in September, as Black Book’s latest monthly report showed its Used Vehicle Retention Index falling 3.1%, or 4.6 points, to 139.7 from August’s 144.3. The Index now sits 3.3% below its September 2025 reading of 144.4.
The Index measures the wholesale average value of two- to six-year-old used vehicles as a percentage of original typically equipped MSRP. It is weighted by registration volume and adjusted for seasonality, vehicle age, mileage, and condition.
Full-size pickups, minivans, midsize cars, and full-size crossovers/SUVs posted some of the more notable declines. Sporty cars were the only segment to gain month over month, while prestige luxury and near-luxury cars held up better than the broader market.
Black Book’s weekly figures showed the same general trend. For the week ending Sept. 26, overall wholesale depreciation was 0.71%, more than twice the 2017–2019 average decline for the same week. Auction conversion was 57%.
Laura Wehunt, Black Book’s vice president of data and analytics, said depreciation is expected to continue through the fourth quarter as seasonal pressure and manufacturer incentives weigh on used-vehicle values.
For independent dealers, softer wholesale values could create opportunities to acquire inventory at lower prices heading into year-end. At the same time, the faster pace of depreciation increases the risk of holding inventory that loses value before it sells.
