Judging mileage-boosting products
Scientific methods are available to verify claims made by manufacturers of “mpg-enhancing” products. Check these products before you get taken for a ride.
By Paul Richards
With fuel being the number one material expense in any carrier’s budget, fleets looking to cut costs can make tasty prey for unscrupulous purveyors of products that promise fuel-economy improvements.
Unfortunately, many products don’t live up to such lofty promises, so it’s no wonder that many fleets tune out such claims and never give the products a chance. Yet, ignoring all mpg-improvement claims could prove costly, because somewhere in the mix, there may be products that actually do what they say.
What all “fuel-economy-enhancing” products have in common is that their promises can be measured, and there are scientific methods of quantifying improvements in mpg. As the late, great Don Dawson – former vice president of maintenance for Akron, Ohio-based Roadway Express – once told CCJ, “You can usually tell [what products work] without too much trouble. There are indisputable laws governing matter and energy. If something works, the results are measurable. In other words, you can’t fool Mother Nature.”
Sometimes a product’s worth can be pre-assessed by checking the validity of its premise. For example, Dawson was approached to try a device claimed to increase fuel economy by decreasing exhaust back-pressure.
He obliged. “That was an easy one,” he said. “Exhaust back-pressure is something we can measure. We installed an exhaust pressure sensor and took readings with and without the device in place. There was no difference, so we didn’t buy it. Simple.”
Fleets are advised, however, not only to determine whether a product produces a beneficial result, but also to ensure that it doesn’t do any harm to vehicles, drivers or the environment.
Recommended insurance
Recommended Practice RP 1115 from the Technology & Maintenance Council (TMC) was drafted with the assistance of equipment users, truck manufacturers and suppliers, and specifically is intended to provide end users with guidelines on how to qualify products that claim to improve fuel economy in heavy-duty trucks.
TMC has investigated many such products, and offers the following broad, product-evaluation guidelines to fleet executives:
• The product must be readily available on the market. •The product must have at least three Class 8 truck customers.
• The suppliers of the product must have an SAE/TMC fuel economy test run to verify the fuel economy claim. The results must reveal who administered the test, and must provide a description of the vehicles used, any aerodynamic devices used, the vehicle speed at which the test was run, and the road course used. SAE/TMC on-road fuel economy tests (Type II, III or IV) were developed jointly by TMC and the Society of Engineers (SAE) of Warrendale, Pa., and are regarded as the only scientific, accurate and repeatable methods of evaluating products that claim to boost fuel economy.
Many such products come with official-looking test results from credible laboratories, which show that the products work. But while laboratory testing has its place, a laboratory isn’t a truck on the road. A measurable reduction of friction, or an increase in combustion efficiency in a laboratory, doesn’t necessarily translate into an on-road fuel-economy improvement.
The Type IV test (see “Testing fuel economy yourself,” page 26) has emerged as the most desirable for many fleets, since it allows freight to be hauled – hence, revenue to be produced – during the test. However, some find the more involved Type II and Type III tests to be more precise when dealing with very small differences in fuel economy.
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Aerodynamic aids are proven to help trucks slip through the air with less resistance. A full-roof fairing, says TMC, can produce a 15 percent improvement over nothing, while an air dam front bumper is good for 3 percent and side skirts can boost mpg by 3 percent. |
“We used a Type II to test some NASA-designed, trailer aerodynamic devices,” says Duke Drinkard, vice president of maintenance for Southeastern Freight Lines, based in Columbia, S.C., and one of the TMC validators of Type II testing. “We were measuring down to one-tenth of an ounce of fuel.
“I find that the Type II is a good test due to the short trip distance required,” he adds. “It’s hard to find long routes today that will not expose you to traffic problems. Done correctly, the Type II test can and does give you a clear picture of the product being tested.”
Today, when approached by suppliers of claimed fuel-saving devices, Drinkard always insists that they have an SAE/TMC test done. “But they almost never do,” he says. “They either don’t want to spend the money (testing is not cheap), or they’re afraid of the results. They’re gone after a year.”
“I don’t have the time or resources to test every product that comes along,” says Jerry Thrift, senior manager for new product development for Miami-based Ryder Transportation Services. “I tell suppliers, ‘If a product is so great, get behind it, commit to spending the money on an SAE/TMC test, and bring us the results.’ They go away and never come back.”
The third degree
To further help fleet operators avoid being scammed, TMC also has developed a list of questions to be asked about claimed mpg-improving products, such as:
• How long has it been on the market?
• Where can it be purchased?
• What is the cost (initial, installation and cost per mile)?
• What, and over what period of time, is the return on investment?
• Have any current users been successful? Can I contact three users?
• Are there any other test results (other than SAE/TMC fuel economy)?
• Does the product affect emissions?
• What is the product’s useful service life?
• What maintenance is required?
• What warranty is offered?
• Will the product affect the life or warranty of the vehicle or components?
• Are there any handling considerations regarding installation, operation or disposal of the product? If the supplier can’t answer the questions, or if you don’t like the answers, the decision not to buy gets easier to make. Do additives add or take away?
Many products claiming to improve fuel economy are oil or fuel additives. In addition to the previous precautionary steps, the wary fleet executive will obtain assurance that such a product will not degrade critical oil or fuel properties, such as viscosity and ash content (oil); or cetane rating, vapor pressure, stability, cloud point, pour point and flash point (fuel). Specifically for fuel additives, see TMC RP 312, “Qualifying questions to minimize the potential for negative side effects from an aftermarket diesel fuel additive package.”
Safety in numbers
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According to TMC, an on/off cooling fan, compared to a viscous fan, can yield a 1.5 to 5 percent fuel economy improvement. |
In some instances, it’s relatively safe to rely on information gathered by others. For example, TMC has found that:
• an on/off cooling fan, compared to a viscous fan, can yield a 1.5 to 5 percent fuel economy improvement;
• a 12 to 13 CFM air compressor, as opposed to a 15 to 17 CFM unit, can improve mpg by up to .5 percent;
• a 25-inch tractor-trailer gap, vs. a 35-inch gap, can produce a .5 to 1 percent improvement;
• a standard roof deflector, as opposed to nothing, can boost mpg by up to 6 percent, while a full-roof fairing can produce a 15 percent improvement over nothing;
• an air dam front bumper is good for up to 3 percent;
• side skirts also can boost mpg by 3 percent;
• A smooth-side trailer can yield a 2 to 4 percent improvement over an exterior-post design;
• rib drive tires, as opposed to lug, can give a 2 to 4 percent improvement;
• synthetic transmission/axle lube can boost mpg by up to .5 percent in summer, and up to 2 percent in winter. These findings are based on Class 8 tractors coupled to 48- to 53-foot trailers, with maximum GCWs of 80,000 pounds, at speeds of 65 to 70 mph.
In evaluating more exotic products, as well as checking one brand against another, a properly performed SAE/TMC test always will tell the truth.
Just remember to take the right precautions, ask the right questions – and don’t get taken for a ride.
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