By Paul Abelson

The national average price of diesel fuel stood at $3.89 a gallon as October drew to a close. While that is off its high of more than $4, it still represents a large chunk of your operating budget.

You're probably spending between $25,000 and $30,000 each year for fuel for a Class 8 vehicle such as a 10-wheel dump truck. If you could save just 3.6% per truck, you would take a full $1,000/truck out of your budget. That's certainly worth considering.

So you're in your office and you get a call from a sales representative. He claims he can save you 3.5%, or 5%, even 10% on fuel. You certainly want to hear what he has to say.

He may be offering you a new additive, a device that goes into your fuel line, a super-slippery oil, an electronic gadget that controls fuel flow, or some other technology. How do you evaluate these mechanisms?

Testing costs money. You have to decide which trucks to test. It may involve training. You may lose man-hours and vehicle service time pulling your trucks off the road to install the device. You must track and evaluate the results before you can make your decision. And if it doesn't work out, you'll spend even more to remove it.

Obviously, you can't evaluate every product. But the promise of savings is too great to pass up. You need a screening process to rule out items with less of a chance to work for you, while identifying those that could be beneficial.

Does it make sense?

Start by examining the claims. Do they apply to your operations? For example, aerodynamic products developed for over-the-road operations start to make a significant impact at speeds of 50 to 55 mph. The aerodynamics of a snow-plow, dump, or boom truck won't be helped much by wind deflectors and chassis fairings.

Aerodynamic devices can be crossed off the list. But there are others that apply to all vehicles, such as tires and lubricants.

Tires and lubricants work independently of speed: The tire that cuts fuel consumption by 5% at highway speeds will perform the same way in city operations. Fuel-saving lubricants and additives will save during power take-off operations, too.

Once you decide a fuel-saving item makes sense for your operation, how do you determine that it will actually work? Many variables go into fuel economy claims. Routes, traffic, weather, speed, and a host of variables — including the driver — can affect results.

In large fleet operations, there can be a 35% difference in fuel mileage among drivers, even if they drive identically equipped trucks.

Putting claims to the test

The gold standard of fuel economy testing was developed by the Society of Automotive Engineers (SAE) and American Trucking Associations' original Maintenance Council, now known as the Technology & Maintenance Council (TMC).

They collaborated to create SAE J1321 and TMC Recommended Practice RP 1101, the TMC/SAE In-Service Fuel Consumption Test Procedure. After the first version was found to be flawed, it was tweaked to create RP 1102, the Type II procedure.

The test evaluates the fuel economy of trucks with a fuel-saving device or product, compared to trucks without it. This can involve anything from an oil additive to an engine or transmission.

The procedure systematically removes as many variables as possible. Trucks operate on the same routes at the same speeds, staying far enough apart that turbulence from one does not affect the other, yet close enough that both experience the same wind, weather, and traffic.

Trucks are tested multiple times to develop a baseline for each and then the results are compared. The item being tested is added to the test trucks. Routes are then re-run. Drivers are changed, so they can be eliminated as a variable.

To be valid, at least three runs must be within 2% of each other. Inconsistent results are disregarded. The Type II test procedure is accurate within 1%.

A Type III procedure was eventually developed to test items that can be removed from one truck and remounted on another. This category includes air deflectors and different tire compounds or configurations, such as wide-base single tires vs. duals.

Other removable items, such as magnetic devices and hydrogen generators, can be tested with either Type II or Type III tests. A Type IV test is now being developed to test devices during actual service operations.

I don't suggest conducting your own SAE/TMC tests. They are costly — ranging from about $25,000 to more than six figures.

Testing is the responsibility of the supplier. Anyone approaching you with a product that claims to improve fuel economy should have those claims substantiated by a SAE J1321, or TMC Type II or Type III test, conducted according to established procedures by an independent, third-party testing facility.

Without independent verification, claims alone are meaningless. With them, your supplier may be offering you thousands of dollars a year in fuel savings.

— Paul Abelson ( is a former director of the Technology and Maintenance Council (TMC) of the American Trucking Associations, a board member of Truck Writers of North America, and active in the Society of Automotive Engineers.