Compare diesel vs gasoline fuel costs per mile and annual expenses. Factor in different MPG ratings and fuel prices side by side.
Diesel engines are typically 25–35% more fuel-efficient than their gasoline counterparts, but diesel fuel often costs more per gallon. This calculator compares the true cost per mile of diesel versus gasoline vehicles, helping you determine which fuel type is more economical for your driving.
The comparison involves three variables: diesel price, gasoline price, and the MPG difference between the two engine types. Even when diesel costs $0.30–$0.50 more per gallon, its superior fuel economy often makes it cheaper per mile, especially for highway-heavy driving.
This tool is invaluable when shopping for a new vehicle that's available in both diesel and gasoline variants, such as pickup trucks, SUVs, and European sedans.
Whether you drive a compact sedan, a full-size SUV, or a pickup truck, accurate diesel vs gasoline figures help you plan smarter and avoid costly surprises at the pump or dealership. Use this tool regularly to track changes over time and adjust your transportation budget accordingly.
The diesel vs. gasoline decision should be based on cost per mile, not pump price. Diesel's higher efficiency often compensates for its higher pump price, but not always. This calculator removes the guesswork and gives you a clear dollar-per-mile comparison. Results update instantly as you adjust inputs, making it easy to explore different scenarios and find the best option for your driving needs and budget.
Cost Per Mile = Fuel Price ÷ MPG Annual Savings = Annual Miles × (Gas Cost/Mile − Diesel Cost/Mile)
Result: Diesel saves $0.014/mile
Diesel: $3.89/35 = $0.111/mile. Gas: $3.49/28 = $0.125/mile. Diesel saves $0.014/mile. Over 15,000 miles, that's $210/year despite the higher pump price.
Diesel fuel contains about 13% more energy per gallon than gasoline (129,500 BTU vs. 114,000 BTU). Combined with diesel engines' higher compression ratios and lean-burn capability, this results in 25–35% better fuel economy compared to equivalent gasoline engines.
While diesel saves on fuel, consider the complete picture: higher purchase price ($2,000–$4,000), more expensive maintenance, higher resale value (diesels depreciate less), and availability of diesel fuel in your area.
Diesel is most economical for high-mileage drivers (15,000+ miles/year), highway-heavy driving, towing/hauling, and long vehicle ownership periods (7+ years). For city-only driving under 10,000 miles/year, the upfront premium rarely pays back.
Diesel historically tracked close to gasoline prices but has been $0.20–$0.60 higher since 2022 due to increased demand and refining capacity. Winter prices spike further. Long-term, the spread is expected to remain as heating and trucking demand keeps diesel prices elevated.
Usually yes. A diesel getting 35 MPG at $3.89/gallon costs $0.111/mile, while gas at 28 MPG and $3.49/gallon costs $0.125/mile. The diesel must get roughly 20%+ better MPG to compensate for its higher pump price, which most diesel engines exceed.
Diesel vehicles require diesel exhaust fluid (DEF, $10–15 per refill), more expensive oil changes, and periodic fuel filter and injector maintenance. These add $200–$500/year in extra maintenance costs compared to gasoline vehicles.
Yes, diesel engines produce more torque at lower RPMs, making them superior for towing. They're also more fuel-efficient under load. A diesel truck towing may get 15 MPG while a gas truck gets only 10 MPG — a 50% advantage.
If a diesel costs $3,000 more and saves $200/year in fuel, payback is 15 years. If fuel savings are $500/year (high-mileage driver), payback is 6 years. Diesel makes best financial sense for drivers exceeding 15,000 miles/year.
Modern diesel engines with DPF (diesel particulate filters) and SCR (selective catalytic reduction) produce comparable or lower CO₂ per mile than gasoline, due to higher efficiency. However, NOx emissions remain higher, though well within EPA limits.
Not typically. About 50% of US gas stations sell diesel. On major highways, diesel is ubiquitous. In very rural areas or some urban neighborhoods, diesel stations may be less common. Plan ahead in rural areas.