Diesel vs. Gas Trucks: Complete Fleet Vehicle Guide

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Written By: Joe Birren, Fleet Operations Manager - Truck & Upfit Engineering

Diesel vs. Gas — which one is better? If you’re in the market for a fleet of trucks, fuel type may be a top consideration. There are pros and cons to each and with a variety of gas and diesel vehicles on the market, there’s a lot to consider when making the right choice for you and your business needs.

Although your fuel choice will largely depend on your application requirements, there are many factors when comparing the two, including longevity, service/maintenance, towing, total cost of ownership, and more. Let’s compare the two.

Diesel vs. Gas Trucks

Total Cost of Ownership

Initially, diesel engine-equipped trucks have a higher acquisition cost, but you also need to consider the total cost of ownership (TCO). This includes the total fuel, maintenance, depreciation, and financial spend over the truck’s lifecycle.

Longevity & Durability

Diesel engines, when properly maintained, typically have a longer service life compared to their gasoline counterpart. Advances in metallurgy, fuel, and engine management technology have greatly improved durability over the last decade. Engine service life is dependent on the application requirements, operating conditions, and proper maintenance.

Service, Maintenance & Warranty

One key consideration is the service, maintenance, and warranty perspective regardless of OEM or truck class. Do you have a local repair facility or dealership with trained, certified technicians who can handle late model diesel engine repairs and maintenance?  Will you need to travel further out to a dealership if warranty issues arise and your regular service center is unable to handle your service needs?

Fuel Economy

Typically, 30 to 35K annual miles is a good baseline to start seeing the fuel economy advantages of a diesel engine. However, this depends on your application, such as the average payload weight, aftermarket body or equipment requirements, towing, and operating conditions. It’s also helpful to consider projected fuel costs.

Fuel prices overall have fluctuated greatly in the past few months, depending on the regional area of the country. Another fuel alternative is biodiesel which the Department of Energy defines as a “liquid fuel produced from renewable sources.”

Payload Capacity & Towing

Payload capacity refers to how much remaining weight a truck can carry after including all occupants, fuel/fluids, equipment, and cargo weight. A diesel engine can add approximately 800 pounds over a gas engine for the same chassis model, so it’s important to consider this additional weight when doing a payload weight calculation.  Below are a few points to consider, especially while towing:

  • Gross Vehicle Weight Rating (GVWR): This refers to the maximum legal operating weight of a vehicle as specified by the original equipment manufacturer (OEM) and the federal government. This weight rating includes all components such as the chassis, any aftermarket body or equipment, driver/occupants, fuel and fluids, and total payload weight excluding trailers.
  • Trailer Tongue Weight: The optimal trailer tongue weight is typically recommended to be between 10-15% of the loaded trailer weight (depending on trailer type, payload, and application).
  • Gross Combined Weight Rating (GCWR): This refers to the maximum legal combined operating weight of the loaded vehicle and trailer as specified by the OEM and federal government.

Acquisition Cost

When spec’ing a new truck, opting for a diesel engine can add about $9,000 to the purchase price over a gasoline engine. However, if you work with a fleet management partner, you may have access to volume incentives, which can help keep lower your acquisition costs.

Resale Value

Diesel optioned trucks will typically hold their resale value better than their gas counterparts. A fleet management partner, however, can offer remarketing solutions for both diesel and gas-powered trucks to help you find the best deal for your fleet when the time comes.


Modern turbocharged diesel engines typically generate more torque than the gasoline counterpart for a given chassis model. Diesel fuel is denser than gasoline, yielding about 15-18% more energy per gallon, and diesel engines are generally more efficient at converting thermal energy into mechanical energy. If you are consistently hauling heavy payloads and/or towing often, especially in hilly/mountainous regions, the additional torque is something to consider when spec’ing your next truck.

Geographic Location & Refueling

In addition to geographic areas, operation conditions, and terrain, it’s also important to consider if your average daily or weekly routes include refueling stations which carry diesel fuel.  Before spec’ing out your next truck, consider your average routes and refueling stations.


Q: Which industries are a better fit for diesel trucks?
A: Diesel trucks are a good choice for a wide variety of industries, especially those that average 30 to 35K miles annually. Most medium & heavy-duty truck logistics and delivery clients, heavy construction and oil & gas industries often consider diesel trucks.

Q: Which industries are a better fit for gas-powered trucks?
A: Light-to-medium duty gas-powered trucks can have an advantage in metropolitan or highly-populated areas where frequent start-and-stop driving is normal, and the average annual mileage is below 20 to 25K miles. Again, this depends on your application requirements.

Q: Are diesel engines more expensive to maintain?
A: Preventative maintenance on diesel engines is typically more expensive than on a gasoline equivalent. However, depending on fuel prices, application, and mileage, the ROI can significantly offset the additional maintenance spend.

Q: How much longer do diesel engines last?
A: Diesel engines can potentially have a much longer service life than their gasoline counterparts, but this depends entirely on proper maintenance and operation.

Q: Which is better — gas or diesel trucks?
A: There are many variables to consider, and this relates directly to what YOUR application requirements are. The best way to determine this is to work with your fleet management company or contact Merchants Fleet Truck Engineers who can consult with you and determine which truck, and engine option, might be the best solution for your needs.

Q: What is the gas mileage of diesel vs. gas trucks?
A: There are a lot of factors that impact fuel economy. Please call Merchants Fleet, and our expert Truck Engineers will provide a detailed consultation.

Let’s Talk About Your Truck Fleet Needs

Whether you need a gas- or diesel-powered truck, payload, body and upfit equipment, or towing questions, we are ready to help you get moving. Contact Merchants Fleet today if you have any questions or would like more information.