Choosing between a diesel-powered vehicle and one that runs on regular gasoline involves more than just checking prices at the pump. Diesel engines often deliver better fuel economy, but diesel fuel usually costs more per gallon. To find out which option is truly more cost-effective, it’s important to compare real-world fuel efficiency, maintenance, and long-term ownership costs.

Here’s a closer look at how diesel stacks up against regular gasoline, using data from the U.S Department of Energy.

Fuel Efficiency: Diesel’s Big Advantage

Diesel engines are typically more fuel-efficient than gasoline engines. According to the U.S. Department of Energy, diesel vehicles can achieve 20% to 35% better fuel economy than their gasoline counterparts. This efficiency advantage is especially noticeable for highway driving, where diesel engines operate at optimal RPMs for longer periods.

For example:

• A diesel car might average 40 miles per gallon (MPG) on the highway.

• A similar gasoline car might average 30 MPG.

Over thousands of miles, this difference can translate to fewer stops at the pump and significant savings in fuel costs.

Fuel Cost Comparison

While diesel engines are more efficient, diesel fuel itself often costs more per gallon than regular gasoline. National averages reported by the U.S. Energy Information Administration show that diesel prices tend to run 20 to 40 cents higher than regular gas, depending on regional supply and seasonal demand.

This higher price at the pump can sometimes offset the efficiency benefits, particularly for drivers who cover shorter distances or do mostly city driving where diesel engines lose some of their advantage.

Maintenance and Ownership Costs

• Diesel Maintenance: Diesel vehicles typically require more expensive maintenance services, such as fuel filter changes, oil changes with specialized oil, and emissions system upkeep. However, diesel engines tend to be more durable and can last longer with proper maintenance.

• Gasoline Maintenance: Gasoline vehicles have lower routine maintenance costs, and parts and services are usually cheaper and more widely available.

Upfront Vehicle Cost

Diesel vehicles often have a higher purchase price than comparable gasoline models. This initial price difference can range from $1,000 to $4,000 more, according to FuelEconomy.gov.

When factoring total cost of ownership, drivers need to consider whether the fuel savings over time will compensate for the higher purchase price and maintenance expenses.

When Diesel Makes Sense

• High annual mileage (especially highway driving).

• Towing heavy loads (diesel engines have more torque).

• Planning to keep the vehicle long-term to benefit from diesel engine durability.

When Regular Gas Is Better

• Lower annual mileage.

• City or short-distance driving.

• Preference for lower upfront vehicle costs and cheaper maintenance.

Real-World Example

• Diesel Vehicle: 40 MPG highway, diesel at $4.00/gallon.

• Gasoline Vehicle: 30 MPG highway, regular gas at $3.60/gallon.

Driving 15,000 miles annually:

• Diesel cost: (15,000 ÷ 40) × $4.00 = $1,500.

• Gasoline cost: (15,000 ÷ 30) × $3.60 = $1,800.

Despite higher fuel prices, the diesel driver would save around $300 per year on fuel alone—but only if driving primarily on highways.

Final Thoughts

There is no one-size-fits-all answer to whether diesel or regular gasoline is more cost-effective. For high-mileage drivers, especially those who spend a lot of time on highways or need towing power, diesel can offer long-term savings. For most everyday drivers, however, gasoline vehicles still provide better overall value thanks to lower fuel prices, cheaper maintenance, and more affordable vehicle costs.