The national average price of diesel fuel stood at $3.86 a gallon as October drew to a close. While that is off its high of about $4, it still represents a large chunk of your operation's budget.

You're probably spending between $25,000 and $30,000 per year for fuel for a Class 8 vehicle such as a ready-mix truck. If you could save just 3.6 percent per truck, you would add $1000 per truck to your bottom line. 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 that 3.5, or 5, even 10 percent 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 new 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 time and vehicle service time to pull 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 or procedure to eliminate items with less chance to work for you, while proceeding with those that have a greater chance.

The first step

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 ready-mix truck won't be helped much by wind deflectors and chassis fairings.

Aerodynamic devices can be rejected. But there are others that apply to all vehicles. Tires and lubricants are good examples.

Tires and lubricants work independently of speed. Aerodynamic resistance increases with the square of velocity, but rolling resistance and internal friction is linear.

The tire that cuts fuel consumption 5 percent at highway speeds will also save 5 percent in city operations. Fuel-saving lubricants and additives also will save during power take-off operations.

Once you determine that 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 percent difference in fuel mileage among drivers, regardless of the identically equipped trucks they drive.

Finding a solution

The gold standard of fuel economy testing was developed by the Society of Automotive Engineers (SAE) and The 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 compares fuel economy for trucks with the device or product being evaluated against trucks without the item. This could involve anything from an oil additive to an engine or transmission.

The procedure systematically removes as much variability 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 they are compared. The item being tested is added to the test trucks. Routes are then re-run. Drivers are changed to eliminate them as a variable. To be valid, at least three runs must be within 2 percent of each other. Inconsistent results are disregarded. The Type II test procedure is accurate within 1 percent.

A Type III procedure was then developed to test items that can be removed from one truck and remounted on another. Examples are air deflectors and different tire compounds or configurations such as wide-base single tires versus 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 or operations.

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

The 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 an 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 of the American Trucking Associations and is on the board of the Truck Writers of North America. E-mail