September Manheim Index: What the Used-Car Market Number Means for Shoppers

What Cox reported for September

Cox Automotive published its September 2026 Manheim Used Vehicle Value Index update on October 7. The seasonally adjusted, mix- and mileage-adjusted index stood at 205.9, down 1.1% from August and 0.6% from September 2025. Cox separately reported that non-adjusted wholesale prices were down 1.3% month over month and 1.2% year over year. These are measures of wholesale used-vehicle prices, not retail asking prices or a quote for an individual car, according to the Cox/Manheim report.

Some segments moved differently

The September update also reported divergent movement across vehicle types. Cox said its EV index was up 0.6% from August and 4.3% year over year, while the non-EV index was down 1.7% month over month and 1.6% year over year. Those figures describe the wholesale indexes for those segments; they do not establish that every used EV gained value or that every gasoline vehicle lost value. Model, age, mileage, condition, equipment, title history, and local demand can all make an individual vehicle behave differently from a segment measure.

Cox also reported wholesale days’ supply of 28 at the end of September, 2.4 days higher than a year earlier and 1.1 days lower than August. Supply is one indicator of the broader market, not a prediction of how quickly a particular car will sell.

Why the index is not your car’s value

A wholesale index tracks transactions in a specific market channel. Retail asking prices reflect the individual vehicle, preparation, warranty status and the local market. Taxes and transaction fees also affect the buyer’s total cost. Trade-in and private-sale values use different assumptions again. Kelley Blue Book explains that it publishes separate Trade-In Value, Private Party Value, and retail-oriented Used Car Fair Purchase Price measures, using factors including vehicle condition and local market conditions. Those tools are vehicle-specific estimates; they are not the same as the Manheim index.

That difference is especially important when comparing a market headline with an online quote. A broad index can provide context about wholesale trends, but it cannot account for a car’s exact trim, accident history, options, tire condition, service records, or local supply. To see how current retail inventory is presented, compare similar vehicles in used-car listings and match the model year, trim, mileage, and equipment as closely as possible. Asking prices are not the same as completed sales or trade offers.

A practical way to use the update

If you are considering a purchase, use the index as background and compare several vehicles with similar age, mileage, and equipment. Review the vehicle history, ask about condition and warranty coverage, and request the total out-the-door price in writing. The Federal Trade Commission says a dealer’s Buyers Guide identifies whether a used vehicle is sold “as is” or with a warranty and recommends an independent inspection. Its used-car buyer guidance also explains why the history report and inspection serve different purposes.

If you are selling or trading, start with the vehicle itself: VIN, trim, mileage, condition, maintenance, title status, and location. Kelley Blue Book distinguishes trade-in from private-party values; the trade-value page can be one vehicle-specific starting point, but an online estimate is not the same as a final inspected offer. The used-car inspection checklist can also help organize a condition review, though it cannot set the car’s price by itself.