After Dieselgate and the collapse of diesel passenger cars, the assumption is that diesel is over in the US market. Split the used listings by state and it's over in some states and nowhere near it in others.
| State | Diesel share | Item |
|---|---|---|
| Montana | 18.7% | Highest |
| Idaho | 16.0% | |
| New York | 2.7% | |
| Washington DC | 1.4% | Lowest |
Thirteen to one
Nearly one in five used vehicles in Montana runs on diesel. In DC it's one in seventy.
The pattern isn't about environmental attitudes, it's about work. Montana and Idaho are states of long distances, agriculture, construction and towing — the four things diesel is genuinely better at. Torque for hauling, efficiency at sustained highway speed, and engines that treat 300,000 miles as ordinary.
DC is a dense city where nobody tows anything and the average journey is short. Diesel's advantages are irrelevant there and its disadvantages — cold starts, particulate filters that need sustained running to regenerate — are at their worst.
What's actually in the diesel column
Almost entirely trucks. Heavy-duty pickups, work vehicles and vans. The diesel passenger car is genuinely dead in America; the diesel workhorse never wavered.
Which means the state map is really a map of what people do for a living, filtered through what they need to tow. It lines up closely with the four-wheel-drive picture from Colorado's 61% AWD share, and for the same underlying reason.
Buying a used diesel
The engine will outlast the truck. A well-maintained diesel reaching 300,000 miles is unremarkable. High mileage means something different here than it does on a petrol car, so applying normal mileage thresholds will cause you to reject perfectly good vehicles.
The emissions hardware is the expensive part. DPF, EGR, DEF systems and their sensors are what fail on modern diesels, and the bills are severe. This is where a diesel bought in a city — short trips, filters never fully regenerating — is a worse buy than the same truck from a rural state.
Check for emissions tampering. Deleted DPF systems are common on work trucks and illegal. A deleted truck can fail inspection, be unregisterable in some states and cost thousands to put right.
Servicing is regional. In Montana every workshop knows diesels. In a low-share state you're paying dealer rates because the independent expertise doesn't exist locally.
Confirm what the engine actually is. Listings misstate powertrains constantly, and it matters more here than anywhere — a VIN check decodes the engine the vehicle was built with, along with title history and open recalls. Emissions-related campaigns are common on diesels and often go uncompleted.
Frequently asked questions
Which state has the most used diesel vehicles?
Montana at 18.7% of listings, followed by Idaho at 16.0%. Washington DC is lowest at 1.4% and New York at 2.7% — a thirteenfold gap driven by towing, agriculture and long-distance driving.
Are diesel cars dead in America?
Diesel passenger cars effectively are, but diesel trucks and vans never went away. Almost the entire diesel share of the used market is heavy-duty pickups and work vehicles.
Is high mileage bad on a used diesel?
Less so than on petrol. A maintained diesel engine reaching 300,000 miles is unremarkable, so normal mileage thresholds will cause you to reject good vehicles. The emissions hardware, not the engine, is what fails.
What should I check on a used diesel truck?
The emissions system — DPF, EGR and DEF components are expensive to replace. Check for illegal deletes, which can make the vehicle unregisterable, and confirm any emissions-related recall campaigns have been completed.
Denis Kataev is a serial solopreneur and the founder of ForCar. With 15+ years in software engineering and 10 years in SEO, he builds data-driven products end to end — backed by a sharp eye for design. At ForCar he mines proprietary vehicle datasets, turning raw numbers into buying advice you can actually trust.
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