Here is a chart that explains a lot about what's happening on used car lots. Cox Automotive, using Manheim wholesale data, shows how the value of used vehicles has changed so far in 2026, sorted by fuel economy.
The Autopian's Matt Hardigree calls the pattern "obvious," and the thirstier the vehicle, the worse its value has held. The more efficient, the better.
Cox's Jonathan Gregory says the gap between the least and most efficient buckets is about 25 percentage points over nine months. EVs are excluded from this chart.
What's driving it
Fuel costs. Gas prices kept climbing after a record Labor Day, with renewed unrest in the Middle East, and diesel is at record highs, near $6.50 a gallon. When filling the tank hurts, buyers who have a choice start asking what the car costs to run, not just what it costs to buy.
Wholesale prices are also soft overall. The Manheim index was 205.9 in September, down 0.6% from a year ago and 1.1% from August. Cox now expects the year to finish roughly flat, down from the 2% gain it forecast in July. Part of that is a normal seasonal lull and the fading of the spring tax-refund bounce.
Who is getting hit
Large pickups and SUVs lead the weakness. Cox says demand and values for them are falling as owners and buyers absorb the fuel costs. Compact cars and EVs were the only major segments above year-ago values in mid-September.
Diesel is a sharp example. Diesels are only about 3% of Manheim inventory, but with fuel near $6.50 their days' supply rose to 39 days in September, 11 days above the overall market and up 27% from a year ago. .
The math at the pump
Take an illustrative driver doing 12,000 miles a year with gas at $4.50.
A vehicle that gets 18 mpg burns about 667 gallons, or roughly $3,000 a year.
A vehicle that gets 45 mpg burns about 267 gallons, or roughly $1,200 a year.
The difference is about $1,800 a year, or $150 a month, before you count the purchase price.
Real money = real repricing!
What this could mean for car buyers and sellers
If you own a hybrid or a small, efficient car, you may be sitting on stronger resale value than usual.
If you're shopping for a truck or big SUV, this is a buyer's moment. Values are softer and the cars are sitting. You'll still pay for fuel, so do the monthly math before you fall for the discount.
If you're shopping for a hybrid, expect to pay up. The market is already pricing in the savings, so compare a slightly less efficient car against the premium.
If you're thinking about trading in a gas-guzzler, check what it's worth now and what it's likely to be worth in a year. If efficiency demand keeps building, the gap may widen.
If you drive a lot, the pump matters more than the sticker. If you drive a little, the purchase price matters more.
Don't buy a diesel on a whim. Supply is building and fuel is at record highs.
Bottom line
The used car market is telling you something, the price of fuel is part of the price of the car. Efficient vehicles are being rewarded and thirsty ones are being discounted. That can work in your favor whichever side you're on, as long as you price the cost of running the car, not just owning it.