If you're thinking about selling a diesel truck in Texas this fall, Cox Automotive's latest wholesale data is worth a look before you accept the first number. In its Q3 2026 Manheim Used Vehicle Value Index release (October 7, 2026), Cox said that with diesel prices at record highs, days' supply for diesel vehicles at wholesale rose to 39 days, 27% higher than a year ago, and that large pickups and SUVs absorbed more of the fuel-cost impact, with demand and values declining. That's a national wholesale trend, not a price for your truck. But when demand for a type of vehicle softens, one dealer's offer tells you less, and comparing several tells you more.
This post is based on two Cox Automotive pages we read for this article: the Q3 2026 Manheim Used Vehicle Value Index press release and the September 2026 MUVVI trends page.
From the two Cox pages:
What these numbers are: wholesale (dealer-to-dealer auction) values, measured nationally. They aren't retail prices, they aren't Texas-specific, and they don't predict what any single truck is worth.
Days' supply is roughly how long the current inventory would last at the current pace of sales. When it rises, it means vehicles of that type are sitting longer. For a dealer considering your diesel truck, that can matter: a truck that may take longer to resell is a truck some buyers will bid more cautiously on.
That doesn't mean every dealer sees it the same way. One store may have a customer looking for exactly your configuration. Another may already have three on the lot. That gap between dealers is the whole reason competing offers exist.
1. Don't rely on an old estimate. If you priced your truck in spring or early summer, Cox's own data says the market moved since then. Get current numbers.
2. Ask more than one dealer. When a segment softens, offers can spread out. One number gives you no way to tell whether it's low. Several numbers do. Our page on how competing offers work walks through the process.
3. Know your payoff before you compare. If you still owe on the truck, the offer has to be read against the payoff, not the other way around. See selling with a loan: lien release in Texas.
4. Present what makes your truck easier to resell. Service records, both keys, a clean title in hand, and an honest description of any issues all help an appraiser. Our dealer appraisal prep checklist covers the basics.
5. Decide whether you're trading or selling outright. You don't have to buy another vehicle to sell to a dealer. Compare a trade-in number with an outright offer: trade-in vs. selling outright.
Nobody can tell you that with certainty, and neither Cox nor we are predicting where diesel truck values go next. Cox said it's "entering Q4 with our antennas up," watching rising interest rates, declining consumer sentiment, and the conflict in the Middle East. If you need to sell, the useful move is the same either way: get several real offers now and see where they land. If none of them work for you, you've lost nothing by asking.
We wrote about the gap between compact cars and pickups last month in compact cars vs. pickups: Texas trade-in values. The Q3 release is the newer data.
PriceForMyTrade connects vehicle sellers with local dealerships that compete for the car. A few things to know:
We don't promise an instant valuation, and we can't tell you what your truck will bring before dealers see it.
Cox's Q3 data shows diesel vehicles sitting longer at wholesale and large pickups and SUVs absorbing more of the fuel-cost hit. That's a national signal, not your price. If you're selling a diesel truck in Texas, the practical response is to get current offers from more than one dealer and compare them against your payoff.
Ready to see what dealers will offer? Get competing offers. It's free to sellers, first responses typically come the same day (not guaranteed), and offers are confirmed after a physical appraisal.