Making the Right Fuel Choice in Your Next Restroom Service or Delivery Rig

A variety of factors will drive a PRO’s decision to go with either a more common diesel power plant or a gas engine in the next work truck.

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Question: Our company is looking to purchase two new trucks. We need another route truck with a slide-in tank and another truck for pickup and delivery as well as for pulling restroom trailers. In the “diesel versus gas” debate, what do you suggest? 

Answer: The answer is “it depends” because every PRO is unique. From one area of the country to another, from one high/low population center to another, from one size company to another, and from a multitude of other classifications, no two companies are alike. The goal of this column, therefore, will be to present facts, data, questions and options that your company can use to create the framework so you can make the best decision for your company.

Classifications of Trucks

Regardless of fuel type, one of the first decisions to be made is the type of truck(s) that your company needs to handle the job effectively and efficiently. There are eight truck classifications in the U.S. based on the maximum loaded weight of the truck expressed as GVWR (gross vehicle weight rating).

Federal Highway Administration Class System:

1. Class 1 – Light Truck – GVWR up to 6,000 pounds

2. Class 2a – Light Truck – GVWR between 6,001 and 8,500 pounds

3. Class 2b – Light/Medium Truck – GVWR between 8,501 and 10,000 pounds

4. Class 3 – Medium Truck – GVWR between 10,001 and 14,000 pounds

5. Class 4 – Medium Truck – GVWR between 14,001 and 16,000 pounds

6. Class 5 – Medium Truck – GVWR between 16,001 and 19,500 pounds

7. Class 6 – Medium Truck – GVWR between 19,501 and 26,000 pounds

8. Class 7 – Heavy Truck – GVWR between 26,001 and 33,000 pounds. 

A commercial driver’s License (CDL) is required to operate this vehicle class.  

9. Class 8 – Heavy Truck – GVWR over 33,001 pounds. A CDL is also required, at a minimum, to operate this vehicle class.

“Ton” Rating

In the U.S., when first produced, trucks were rated on their payload capacity in tons. These capacities were ½ ton, ¾ ton and 1-ton. Over the years, payload capacities have increased while the ton titles have remained the same. These ratings, therefore, are for comparison purposes only.

Begin Your Analysis Process:

Given that you are an experienced PRO with a fleet of vehicles, compile data on each truck.

1. Vehicle use (route service, unit pickup and delivery, pull event trailers and/or restroom trailers, supervisory/sales) 

2. Vehicle size (light, medium, heavy)

3. Age of vehicle

4. Miles driven per year

5. Annual maintenance and repair costs

6. Fuel mileage

7. Type of fuel (diesel, gas, other)

The information you compile on each existing vehicle will assist in making decisions on a new vehicle. For example, if maintenance and repair costs are significantly higher on an existing older light-class delivery truck, perhaps moving up to a medium class truck would be beneficial. 

In your analysis of the existing fleet, also go beyond the numbers and examine other factors such as the service area (city, suburban, rural), terrain traveled (flat, mountainous, interstate, off road) and days of week in service (occasional, five days a week, every day). This information can be useful in choosing the best features and options for the new vehicle.

Factors to Consider — Diesel or Gas?

In reference to the diesel vs. gas question, here are some general statements we have found in our research concerning each fuel type. Based on the analysis of the existing fleet, the fuel option that meets the needs of the PRO is “best answer.”

1. Gas-engine trucks cost less to purchase. Depending on class and manufacturer, the diesel option for a truck usually costs between $7,000 and $10,000 more than the gas option.

2. Diesel’s engines use about one-third less fuel than comparable gas engines. Some experts suggest that if you are using your vehicle less than 25,000 miles per year, gas may be a better choice. The cost of both fuels can fluctuate dramatically based on economic conditions, but diesel is usually more expensive. 

3. Diesels have a longer useful life and retain more value with higher mileage totals. They are typically equipped with heavier frames, hitches and the engines weigh more as well. 

4. Diesels can pull heavier loads and are the go-to option for power takeoff operations. If you need to pull heavy trailers often, diesel might be a better choice. 

5. Gas trucks have a simplified maintenance and, in general, repair technicians are not as costly. Gas-powered trucks use fewer and less expensive filters and consume less oil, which is a cost savings. Diesel powered trucks are costlier to repair.

6. The differences in fuel economy between the gas and diesel engines depend on the intended use of the vehicle. With light loads, fuel usage is similar. With heavy loads, gas engines work harder and the miles per gallon are reduced. The diesel engine’s mpg drops only slightly with heavier weight.

7. New diesel engines require diesel exhaust fluid, which is needed to meet emissions requirements. This is another added expense to operation of these vehicles.

8. Most diesel engines have an integrated exhaust brake, which slows the truck with back pressure from the turbo. The jake brake reduces wear and tear on the brake system and lowers the risk of brake overheating.

Additional considerations based on our experience

1. Fuel price can also be a consideration depending on miles driven and service area covered.

2. The availability of diesel fuel can be a factor in some geographic locations.

3. Larger trucks generally require CDL drivers and, as with any specialty skill, pay rates will be higher.

4. Insurance varies depending on the size and the age of your fleet vehicles. This is another expense to factor into your decision framework.

5. Consult your certified public accountant about of favorable depreciation schedules for purchase of new vehicles.

6. Monitor current information and trends about industry vehicles through PRO and Pumper magazines, attending industry trade shows (WWETT and PSAI), and staying in communication with the truck dealers and builders you work with.     

How Do These Factors Impact Your Decision of Fuel Type for Your Company?

Based on your specific needs, use these facts to help to make this decision for your company. Do not base the decisions on others’ opinions or on the type of equipment your competitors may or may not be using. Once purchased, record and monitor the costs, performance and statistics on the new vehicle(s) just as you are doing with the rest of the fleet.


“It depends” is important to your company and to your company only. Identify the factors that are important in choosing the type of vehicle fuel power that your company will employ.

As technology is constantly changing and evolving, use your decision framework to evaluate new fuel options such as natural gas, propane, hybrid electric and electric. Always be open to change!  


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