Boosting MPG: No magic bullet

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Wouldn’t it be nice to pour something in or bolt something on, and see a significant increase in fuel economy from your vehicles? Sadly, experts agree that such things don’t really exist.

Especially in times of record fuel prices, it’s tempting to believe that an aftermarket product can yield an mpg advantage – but keep your eyes open. Such products generally take the form of fuel or oil additives, and bolt-on hardware. While some may provide other limited benefits, none, say experts, are effective at significantly boosting fuel mileage.

Adding little to your tank
While there are legitimate additives used to address specific operating challenges – like those that prevent fuel gelling in extremely cold climates – “I’ve never found one that improves fuel economy,” says Darry Stuart, president of DWS Fleet Management Services, based in Wrentham, Mass.

Stuart is a fleet manager with 30 years’ experience, and he’s a past recipient of CCJ’s Career Leadership Award. “If you’re convinced that one might work, test it,” Stuart says. “Just commit to it. Make sure you have a system in place to make sure it’s being added at the recommended interval and dosage. Then make sure it’s cost-effective – that is, determine if the cost of the product outweighs any benefit it might provide. Even if the cost/benefit is a wash, what good is it?”

“We’ve not found a fuel additive that changes combustion,” says Zack Ellison, Cummins’ director of customer technical support. “But we have found some that actually aid particulate filter regeneration.”

“There are no miracles,” says Rodica Baranescu, manager of fuels, lubes and coolants at International. “But say you’re using a substandard fuel that doesn’t meet industry specs for lubricity. Then a lubricity additive could slightly improve mpg – along the order of 1 to 2 percent.” Baranescu cautions, however, about overdoing it. “Additives are like medicine,” she says. “Some can improve certain fuel characteristics that might be lacking, but like overmedication, too much can do harm.”

As for oil additives, “If an additive thins viscosity, there could be some benefit, due to less churning loss, just the same as if you used a lighter-weight oil,” Ellison says. “But then you run the risk of sacrificing engine longevity.”

The Technology & Maintenance Council advises maintenance executives 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.

International agrees in its standard statement: “There are potential concerns with additives, including: compatibility with the additives of the oil/fuel; other effects of the additives that may not be beneficial; correct dosage; and sulfur, ash and phosphorous levels for use in 2007 products.” The potential problem here is aftertreatment compatibility.

Caterpillar goes a step further in its statement: “As long as commercial products meet Caterpillar recommended classifications/specifications for the compartment they will be used in, they should provide acceptable performance, but the use of any product other than Caterpillar’s is at the customer’s risk.”

Left to their own devices
There are scores of bolt-on aftermarket products claimed to provide a fuel-economy benefit. Take fuel-line magnets, or “catalysts” as they are sometimes called. These supposedly work by energizing, or aligning, fuel molecules for improved combustion. “I don’t believe it,” says Stuart. “If it were true, they’d be standard equipment.”

“If they worked, we would supply them,” agrees Baranescu.

“It’s good for a laugh,” says Ellison. “Even if they could align fuel molecules, by the time the fuel went through a high-pressure pump and was forced through injector holes the size of pin points, they wouldn’t stay that way. They can’t change fuel Btu content. If they could, you’d have something.”

Another oft-advertised device is the swirl inducer. Installed on the intake side of an engine, it has vanes that are supposed to impart a swirl to incoming air, which, say suppliers, improves combustion. “Any restriction you put in the intake airflow can’t improve performance,” insists Ellison. “And even if it did improve swirl, the air still has to go through a turbo spinning at high speed before it gets to the cylinder.” Even if the device were installed aft of the turbo, says Ellison, the air still needs to go through piping, a manifold and intake valves. In other words, the “swirl” would decay almost immediately.

“Engine manufacturers have been working for years to optimize turbulence,” notes Joel Hiltner, chief engineer of combustion systems for Hiltner Combustion Systems, an independent combustion research shop. “The notion that you could throw on an aftermarket device and make an improvement seems unlikely.”

Then there are onboard hydrogen generators. These use electrolysis to extract a tiny amount of hydrogen from water and inject it into the intake stream, for a claimed increase in fuel economy. The first flaw is that producing hydrogen in this manner takes more power in the form of parasitic alternator loads than the hydrogen can return. “It makes less energy than it consumes,” sums up Hiltner. “We’ve done studies on these systems and found no benefit.”

Some suppliers of the devices claim that the hydrogen is not used as a supplemental fuel, but as a combustion catalyst. “There’s still no science behind it,” says Ellison. “I know fleets that have tested these things, found no benefit and turned them back in.”

“We once did the energy balance on this one,” recalls Pedro Ferro, former general manager of ArvinMeritor Emissions & Brakes before the emissions division was sold, and now president of Webb Wheel. “We came up with the need to design a special trailer, just to pull a 250kW gen-set behind the truck, so we could yield enough hydrogen from the water to do what they say it does. But even if you can yield enough hydrogen, injecting it in a diesel cycle is a whole other story. It produces no benefit.

“I later watched a video on a passenger car that supposedly ran on water,” Ferro chuckles. “I went home and tried to light up my garden hose.”

How do they do it?
Sometimes, purveyors of such additives and devices are well-intentioned; sometimes not. “I think half of them think the products work, but have no understanding of why they don’t,” Hiltner says. “I think the other half knows they don’t work, but will sell them anyway.”

One approach is to let the buyer convince himself that the product is responsible for an improvement, when it may be unrelated. For example, says Ellison, fuel economy is always better in warm weather. So if an operator tries a product in the spring, he might assume incorrectly that the product was responsible for the mpg gain.

Also, if there’s a problem that is corrected when the product is added, the issue gets clouded. For example, says Hiltner, “If I take a spark-ignited engine with badly corroded spark plugs, and I replace them with my ‘magic plugs,’ the efficiency will, of course, improve. But it will not improve any more than if I had replaced the corroded spark plugs with new off-the-shelf plugs. One should always be leery of any device that has claimed benefits without a clear explanation of what physical process is leading to the improvement.”

“The best road to better fuel economy is good maintenance and proper driving techniques,” says Baranescu. “That means using the right fuel and lubes, and following the ecommendations in your owner’s manual.”

Don’t go it alone
Recommended Practice RP 1115 from the TMC was drafted with the assistance of equipment users, truck manufacturers and suppliers, and is intended specifically to provide end users with guidelines on how to qualify products that claim to improve fuel economy.

TMC investigated many such products and offers the following broad product-evaluation guidelines:

  1. The product must be readily available on the market.
  2. The product must have at least three Class 8 truck customers.
  3. The product must have an SAE/TMC fuel economy test run to verify the fuel economy claim. The results report 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 and IV) were developed jointly by the Society of Engineers (SAE) and TMC, 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.

When approached by suppliers of claimed fuel-saving products, Duke Drinkard – vice president of maintenance for Columbia, S.C.-based Southeastern Freight Lines – always insists that they have an SAE/TMC test done. “But they almost never do,” Drinkard 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.”

Be an interrogator
To further help fleet operators avoid being scammed, TMC 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?
  • 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 these questions, or if you don’t like the answers, the decision not to buy gets easier to make.

While some fleet managers may opt to perform a Type II, III or IV test on their own, there are independent labs and consultants who can do it for them. Fleet operators supplying their own equipment should expect to pay $7,000 to $10,000 plus expenses (travel, lodging, etc.).

Two respected testers are the South-west Research Institute, San Antonio, Texas, 210-684-5111 or this site; and Claude Travis and Associates, Grand Rapids, Mich., 616-364-0869.

To order a copy of RP 1109 “Type IV fuel economy test procedure,” RP 1102 (Type II test), RP 1103 (Type III test) or any other Recommended Practice, call TMC at 703-838-1763 or go to this site.

The right way to do it
Goodyear goes by the book with Fuel Max test

When Goodyear introduced its new Unisteel tires with Fuel Max technology last year, and claimed that they were more fuel-efficient than its older designs, the company invited the press to come to its San Angelo Proving Grounds in Texas and observe an SAE/TMC Type II fuel consumption test, pitting old against new.

In this case, two identical tractor-trailers – a control rig and a test rig with the same powertrain, mileage, horsepower, GCW, tires, pressure, etc. – were fitted with removable, portable fuel tanks, which were weighed before and after identical runs of at least 28 miles at the exact same highway speed. Fuel consumption was measured by tank weight, and the two rigs were compared as a baseline. Three runs, which must produce results within 2 percent of each other, were made. In this case, the two rigs’ fuel consumption figures were consistently within 1 percent of each other.

Next, the test was repeated, with the control rig unchanged, and the test truck fitted with the component to be tested – in this case, the new tires. Over the course of three runs, with results within 2 percent of each other, the test truck had consumed about 7.5 percent less fuel per run.

Claim made, point proved, case closed.