If you tow heavy loads often and plan to keep the truck for years, buy diesel; for daily driving and occasional towing, buy gas. Diesel brings better mpg and stronger low-speed pulling, but a higher price and more complex upkeep. Gas costs less to buy and service. FuelEconomy.gov and the U.S. Department of Energy supply the figures below.
TL;DR:
- Diesel engines can be 20% to 50% more fuel efficient in some vehicles, but sample fuel prices were $6.38 per gallon for diesel and $4.47 for regular.
- Compare five year ownership costs by adding projected fuel spending, scheduled maintenance, and depreciation, using your annual mileage, local prices, towing pattern, and expected resale value.
- Diesels require DEF refills, carry costly DPF and injector repair risks, use more oil, and may need specialist service; inspect service records before buying used.
- A diesel’s heavier engine can reduce legal payload, so check payload against trailer tongue weight and cargo rather than relying on its tow rating alone.
Table of Contents
- How do diesel and gas trucks compare at a glance?
- What do fuel economy and fueling costs look like?
- Why does a diesel truck cost more to buy?
- How do maintenance and emissions systems differ?
- Does diesel longevity justify the cost over five years?
- Which truck fits your driving: a decision guide
- Can you find diesel as easily as gas?
- Are there incentives or tax benefits for buying a truck?
- Our view on picking a used truck
- How can we help you find the right used truck?
- FAQ
- Sources
How do diesel and gas trucks compare at a glance?
- Upfront cost: Gas trucks cost less to buy. Diesel trims carry a premium that only pays off with enough use.
- Fuel economy: Diesel typically wins on mpg, though diesel fuel often costs more per gallon.
- Maintenance: Gas engines have simpler exhaust systems. Diesels add emissions hardware and larger service items.
- Longevity and resale: Diesel engines are built for long service lives and often hold value well when maintained.
- Towing: Diesel's low-end torque suits heavy, repeated towing. Gas handles many lighter trailers well.
- Payload: A heavy diesel engine can reduce legal payload, so a higher tow rating does not always mean more cargo capacity.
Your annual miles, towing frequency and how long you keep the truck decide which column wins.
What do fuel economy and fueling costs look like?
Diesel's efficiency edge starts with the fuel itself. Diesel fuel contains more energy per gallon than gasoline, and diesel engines convert more of that energy into work. The Department of Energy's primer says diesel engines can be 20% to 50% more fuel-efficient than gasoline engines in some vehicles, converting 40–50% of fuel energy to work versus 25–35% for gasoline. FuelEconomy.gov agrees that diesel vehicles are more fuel-efficient and have more low-end torque than similar gasoline engines.
The 2025 Fuel Economy Guide estimates annual fuel cost using 15,000 miles per year and sample prices of $4.47 per gallon for regular and $6.38 per gallon for diesel. That price gap can eat into the mpg advantage, so run your own numbers.
The formula is simple: annual miles ÷ mpg × price per gallon. For an illustration, use your trucks’ actual mpg and annual miles. Plug in your local prices to see who wins. Towing and heavy loads cut mpg for both, so use your real driving pattern.
The same guide notes that manufacturers commonly approve B5 biodiesel, and some models approve up to B20. Check your owner's manual before using any blend.
Why does a diesel truck cost more to buy?
Diesel trims need stronger engines, transmissions and emissions systems, and buyers pay for that hardware. Cars notes that gas pickups cost less and suit lighter-duty use, while diesels cost more upfront but typically return better fuel economy and resale for heavy, repeated towing. Reporting from Edmunds via AP News describes a premium of several thousand dollars on light-duty diesel options that buyers have to justify by their use and ownership plans.
Resale softens that premium. A diesel that has been maintained and worked hard tends to hold its value better, which can narrow the lifecycle gap if you keep the truck a long time.
The practical rule is plain. If you won't keep the truck long, or you won't tow often, the diesel premium rarely pays back. If you tow every week and drive high mileage, the higher price starts to make sense. Paying for capability you never use can be an avoidable expense.
How do maintenance and emissions systems differ?
Modern diesels clean their exhaust with diesel exhaust fluid (DEF) and a diesel particulate filter (DPF). DEF has to be refilled, and a clogged or failing DPF can bring expensive repairs. High-pressure fuel injectors can also need costly overhauls even when the engine block itself is durable.
Routine service differs too. Diesels hold more oil, run on different service intervals, and sometimes need a specialist who is harder to find. Each of those adds time and cost to ownership.
Gas trucks have simpler exhaust systems, and routine work is generally easier and cheaper. They are not immune to big repairs, though. A gas engine that has been overloaded or neglected can fail just as expensively.
This is where inspection matters on a used truck. Service records, DEF and DPF history, and injector condition tell you far more than the odometer does. Ask whether the previous owner towed heavy and how the emissions system was handled.
Does diesel longevity justify the cost over five years?
Diesel durability is a major reason fleets choose them. The Department of Energy's heavy-duty engines chapter says truck decisions are driven by duty cycle, and diesel dominates many truck classes because of efficiency and durability. Diesel engines can offer long service lives, but actual longevity depends on the vehicle and its maintenance.
To frame a five-year total cost of ownership, add three things:
- Projected fuel spend (miles ÷ mpg × price).
- Scheduled maintenance, including DEF, filters and oil.
- Expected depreciation, meaning what you paid minus what the truck will fetch.
Diesel tends to come out ahead when you combine high mileage with heavy use. Low miles and light towing favor gas, because the fuel savings never accumulate enough to cover the extra purchase price and upkeep.
Don't rely on averages. Use your own annual miles and towing frequency. If you don't plan to keep a truck for a long time, the diesel premium is unlikely to be recovered through fuel savings alone.
Which truck fits your driving: a decision guide
Match the engine to the job:
- Commuter: Gas. Short trips and light loads never reward diesel's extra cost.
- Weekend camper: Usually gas, unless the trailer is heavy and the trips are long.
- Contractor: Diesel if you tow heavy equipment daily; gas if loads stay modest.
- Long-haul, tow-intensive driver: Diesel, for torque, mpg under load and engine life.
Ask yourself these first: How many miles do you drive each year? How often do you tow, and how heavy is the trailer? How long will you keep the truck? How much payload do you need? Can you easily reach diesel fuel and qualified service?
Then work through these steps:
- Estimate your annual fuel cost with both engines.
- Check owner history on any used truck you like.
- Schedule a pre-purchase inspection with someone who knows diesels.
- Use a test-drive checklist to catch cold-start and brake faults.
Pro Tip: Do the towing capacity math before you shop, because a big tow rating means little if payload runs out first.
Our payload vs towing guide covers why those two numbers differ. A heavy diesel engine can reduce legal payload compared with an equivalent gas engine.
Can you find diesel as easily as gas?
Gas is available at nearly every station, while diesel pumps are less universal. In and around cities, finding diesel is rarely a problem. On rural back roads or in smaller towns, you may have to plan your fill-ups.
Pump layout matters for towing. Many diesel pumps sit at truck lanes or the edge of the lot, which helps if you pull a long trailer. Stations without those lanes can be awkward with a trailer hitched.
Price is the other half of availability. As the sample figures in the 2025 Fuel Economy Guide show, diesel can cost noticeably more per gallon than regular gasoline, so the mpg advantage has to cover that gap. Prices change constantly, so check your local stations before you decide.
Service access follows the same pattern. Gas trucks can be serviced almost anywhere, from quick-lube shops to any independent mechanic. Diesel-capable shops are fewer, and DEF refills are another stop to plan if you drive long distances.
A useful habit: map your regular routes and note where diesel is sold. If your weekly route has plenty of options, availability is a non-issue. If you travel remote areas, gas offers more freedom, and a diesel owner needs to fill up earlier than feels necessary. For most buyers, this factor shouldn't decide the question alone, but it does belong on your checklist.
Are there incentives or tax benefits for buying a truck?
Incentives rarely tilt the choice between diesel and gas on a used truck. Most purchase incentives and tax programs target new vehicles, and rules change often, so the right first stop is the IRS or your state revenue office, or a tax professional who can confirm what applies to you.
Business use is where tax questions come up most. If you buy a truck for work, deductions and depreciation rules may apply, and they can depend on vehicle weight and how much of your driving is business use. That is a conversation for your accountant, not something to assume from a general article.
Used buyers should focus on what they can control. Sales tax and registration fees apply to both engine types in your state, and a diesel's higher price can mean higher tax in dollars. The difference in cost between engines matters more than any incentive you might hope to catch.
Financing also changes the math. A lower purchase price means a lower monthly payment, which can offset higher fuel costs on a gas truck. A diesel's larger loan can strain a budget if you are not towing enough to benefit.
Our advice: build the numbers on price, fuel, maintenance and resale first. Treat any tax benefit as a bonus you confirm with a professional, not as a reason to choose an engine.
Our view on picking a used truck
We sell used trucks with a low-pressure, inspection-first approach. A thorough inspection is how we spot maintenance or emissions-system problems before you buy, and that matters most on a diesel. We offer tailored financing and a car-finder service for buyers who haven't settled on an engine. Book a test drive and a pre-purchase inspection to confirm your choice on the actual truck.
— Elmwood
How can we help you find the right used truck?
Whether the duty cycle points you to diesel or gas, we can help you act on it. Our inspected inventory covers used trucks, cars, SUVs and vans, so you can compare engines on real vehicles instead of spec sheets.
If the numbers say you need a specific truck, our Car Finder service will look for a diesel or gas model that matches your tow weight and budget. Our tailored financing options serve a range of credit histories, including buy here, pay here solutions, and you can apply for used car financing online before you visit. Have a vehicle to trade? Start with our trade-in page.
Our sales team isn't paid on commission, so you get honest answers about whether a diesel premium makes sense for your driving. Browse the inventory, apply for financing, or request the Car Finder service today, and bring your annual mileage and towing plans. We'll help you run the numbers and put the right truck in your driveway.
FAQ
What trucks last longer, gas or diesel?
Diesel engines are generally built for longer service lives, and fleets choose them for durability, according to the Department of Energy. Maintenance history still matters more than fuel type. A well-kept gas truck can outlast a neglected diesel.
What are the downsides of a diesel truck?
Diesels cost more upfront and add emissions hardware such as DEF and DPF systems. Repairs on injectors and filters can be expensive. Heavy engines can also reduce payload.
Should I buy a diesel truck as a daily driver?
Usually not, unless you also tow heavy loads often or drive very high mileage. Short trips and light loads rarely repay the diesel premium. A gas truck suits most commuting better.
Is diesel worth the extra money?
It is when you tow heavy, repeated loads and keep the truck for many years. Cars.com says the premium only pays off with sufficient use. Run your own fuel, maintenance and resale numbers first.
Sources
- Diesel Power: Clean Vehicles for Tomorrow
- Diesel Vehicles
- Cars
- Edmunds: Are diesel engines on light duty trucks worth it? | AP News