The short answer
Choose a diesel truck if you tow heavy often, rack up high annual mileage, or keep trucks past 300,000 miles — diesels return 20–35% better fuel economy and out-tow gas. Choose gas if you tow occasionally and want the lowest cost: the diesel option adds $8,000–$12,000 up front and $500–$1,500 a year in upkeep.
What is the fuel economy difference between a diesel and gas truck?
A diesel truck typically returns 20–35% better fuel economy than the same truck with a gas engine when running unloaded, and the gap widens when towing the same load. A 2026 Ram 1500 with the 3.0L diesel is EPA-rated at 22 city / 32 highway mpg, versus 15 city / 22 highway for the 5.7L Hemi gas V8.
| 2026 Ram 1500 | Diesel (3.0L) | Gas (5.7L Hemi) |
|---|---|---|
| City mpg | 22 | 15 |
| Highway mpg | 32 | 22 |
| Economy edge unloaded | ~20–35% in the diesel's favor | |
Diesel fuel also carries more energy per gallon, so the mpg advantage holds up under load when a gas engine has to work hardest. EPA estimates for both engines are published at fueleconomy.gov. To squeeze more from either tank, see how to improve your gas mileage.
How much more does a diesel truck cost to buy?
Choosing the diesel engine on the same truck typically adds $8,000 to $12,000 to the purchase price. That premium pays for a heavier-duty block, turbocharging, emissions hardware, and a stronger drivetrain. On a financed truck it raises your loan balance and monthly payment, so the upfront gap is the first hurdle a diesel has to earn back.
- Engine option cost: roughly $8,000–$12,000 over the base gas engine on the same trim.
- Financing impact: a larger amount financed means higher interest paid over the loan.
- Resale offset: diesels often command a resale premium, recovering part of the upfront cost.
Before you commit, weigh the premium against your total ownership budget — see our breakdown of the annual cost of car ownership.
Is a diesel engine better than gas for towing?
Yes, for heavy and frequent towing. A diesel makes far more low-end torque than a comparable gas engine, so it pulls heavy trailers with less strain, holds speed better on grades, and runs cooler under sustained load. Heavy-duty diesel pickups also carry the highest tow ratings on the market, with top configurations exceeding 30,000 pounds.
For light or occasional towing, a modern gas V8 or turbo V6 handles the job fine and avoids the diesel's cost premium. Match the engine to your real trailer weight, not the maximum on the brochure. Compare full-size options in our Ford F-150 vs. Chevy Silverado and Silverado vs. Ram 1500 guides.
How much more does a diesel truck cost to maintain?
A diesel truck typically costs $500 to $1,500 more per year to maintain than an equivalent gas truck. Diesels hold more oil per change, require diesel exhaust fluid (DEF) top-offs, and use emissions hardware such as the diesel particulate filter (DPF) that can be costly to service or replace once the warranty ends.
- Oil changes: larger oil volume and diesel-spec oil raise the per-service cost.
- DEF fluid: an ongoing consumable that gas trucks do not need.
- DPF and emissions: particulate filter service or replacement can be a major out-of-warranty bill.
- Fuel system: high-pressure diesel injectors and pumps are expensive if they fail.
How long does a diesel truck engine last compared to a gas engine?
A well-maintained diesel truck engine commonly reaches 300,000 to 500,000 miles or more, while a gas half-ton typically reaches 200,000 to 300,000 miles with similar care. Diesels are built with heavier internal components and lower operating speeds designed for sustained high-load work, which is why they routinely outlast gas engines when serviced on schedule.
Longevity only pays off if you keep the truck long enough to use it — a diesel that's traded at 120,000 miles never recovers its premium. Read more on how long a car engine lasts and how long cars last overall.
Is diesel fuel more expensive than gasoline — and does it matter?
Usually yes. Diesel has historically run about $0.50 to $1.00 more per gallon than regular gasoline at U.S. pumps, per EIA data. Whether it matters depends on your driving: a diesel's 20–35% better economy can fully offset the higher per-gallon price for high-mileage drivers, while low-mileage owners feel the premium without recovering it.
Diesel prices swing with crude markets and seasonal demand, so the gap is not fixed. Track current and historical national averages at the U.S. Energy Information Administration before you assume a diesel will save you money.
Who should buy a diesel truck — and who should stick with gas?
Buy a diesel if you tow heavy regularly, drive high annual mileage, or plan to keep the truck past 250,000 miles — that's where the 20–35% fuel savings and long engine life pay back the $8,000–$12,000 premium. Stick with gas if you tow occasionally, drive mostly empty, or want the lowest purchase price and simplest upkeep.
| If you... | Better choice |
|---|---|
| Tow heavy trailers frequently | Diesel |
| Drive 25,000+ miles a year | Diesel |
| Keep trucks past 300,000 miles | Diesel |
| Tow occasionally or haul light | Gas |
| Want the lowest purchase price | Gas |
| Prefer the simplest maintenance | Gas |
Frequently asked questions
How much better is a diesel truck's fuel economy than gas?
A diesel truck typically returns 20–35% better fuel economy than the same truck with a gas engine when running unloaded, and the gap widens further when towing. A 2026 Ram 1500 diesel is EPA-rated up to 32 mpg highway versus 22 mpg for the gas Hemi.
How much more does a diesel truck cost than gas?
Choosing the diesel engine on the same truck typically adds $8,000 to $12,000 to the purchase price. That premium covers the heavier-duty engine, emissions hardware, and stronger drivetrain components, and it usually carries into resale and financing as a higher loan balance.
Is a diesel engine better than gas for towing?
Yes, for heavy and frequent towing. A diesel makes far more low-end torque than a comparable gas engine, so it pulls heavy trailers with less strain and holds speed better on grades. Heavy-duty diesel pickups also carry the highest tow ratings, often exceeding 30,000 pounds.
How much more does a diesel truck cost to maintain?
A diesel truck typically costs $500 to $1,500 more per year to maintain than an equivalent gas truck. Diesels use more oil per change, require diesel exhaust fluid (DEF), and have emissions hardware like the DPF that can be expensive to service or replace out of warranty.
How long does a diesel truck engine last compared to gas?
A well-maintained diesel truck engine commonly reaches 300,000 to 500,000 miles or more, while a gas half-ton typically reaches 200,000 to 300,000 miles with similar care. Diesels are built with heavier internal components designed for sustained high-load operation.
Is diesel fuel more expensive than gasoline?
Usually yes. Diesel has historically run about $0.50 to $1.00 more per gallon than regular gasoline at U.S. pumps, per EIA data. A diesel's better fuel economy can offset that higher price, but the per-gallon premium matters most for low-mileage drivers.
Who should buy a diesel truck instead of gas?
Buy a diesel if you tow heavy regularly, drive high annual mileage, or plan to keep the truck past 250,000 miles. Stick with gas if you tow occasionally, drive mostly empty, or want the lowest purchase price and simplest maintenance for typical commuting and light hauling.
Sources
CarsLens is editorial guidance, not individualized advice. This page draws on fueleconomy.gov (EPA/DOE) and the U.S. Energy Information Administration.