TAMPA, Fla. – If you’ll forgive the obvious pun, the latest frontier in fuel economy involves some out-of-the-box thinking. Specifically, manufacturers and fleets alike are exploring innovative ways to include trailers in fuel-saving strategies.

“You need to look at the tractor and trailer as a system,” stressed Sam Waltzer of the US Environmental Protection Agency’s SmartWay Transportation Partnership, during a recent presentation to the Technology & Maintenance Council.

Since 64% of the trailers on US roads are van trailers, the program designed to promote fuel-efficient business practices will offer its stamp of approval to any 53-foot van trailers that improve fuel economy by 5%. California already requires gains like these to be made on trailers built since 2011, and reefers in the western state need to improve fuel economy by 4%.

The gains themselves can come through a series of steps. Tires with a reduced rolling resistance, for example, will improve fuel economy by 1.5% on their own. Further improvements can come from a combination of aerodynamic fairings, side skirts and boat tails.

Michael Roeth, executive director of the North America Council for Freight Efficiency, said that many companies like Challenger Motor Freight are already embracing several enhancements.

The Ontario-based fleet was included in a 2011 study – along with Schneider National, Werner, Con-Way, Ryder, and CR England – to measure which fuel-saving enhancements were being adopted.

Results tracked the use of 60 available technologies, and the fleets were using about half of the available options in 2010, compared to 30% in 2003.

With the changes in place, each tractor-trailer saved about $4,500 in fuel each year, enjoying average fuel economy of 36.7 litres per 100 kilometres. Without the changes, they would have been lucky to hit 39 litres per 100 kilometres.

There should be little surprise that fleets turned to the fuel-saving options when diesel prices spiked in 2008, but the businesses also continued to invest in the technologies when the prices dipped in 2009 and 2010, Roeth said. And while trailer features such as boat tails, trailer skirts, and systems to control the gaps between tractors and trailers have not been around long, there has been a rapid increase in related interest.

Challenger Motor Freight is also spec’ing every new trailer so it can be used in a Long Combination Vehicle, he added. “It was very impressive to us.”

Enhancements simply need to be matched to the specific ways that vehicles are used. From 0-55 km/h, most fuel economy improvements come from the powertrain, said Sandeep Kar, global director, commercial vehicle research at Frost and Sullivan. From 55-95 km/h, the difference is made with tires. But above that, the differences come from aerodynamics.

Another area to consider will be the “soft” technologies such as telematics, which can remotely control equipment like reefers. One in every 10 North American trailers already has some form of telematics hardware in place, and that is double the amount that existed seven years ago. These tools offer “the easiest and best ways” to address trends like green legislation and rising fuel prices, he said.

Supported with $2 million in funding from the US Department of Energy, Navistar is using a series of wind tunnels, track tests and fleet evaluations to find options that would improve tractor-trailer fuel economy by 15%.

Since 2008, these tests have explored multiple trailer gaps, fairings, skirts and boat tails, and wide-base single tires, said Kevin Golsch, chief engineer, aerodynamics at Navistar. The best combination has so far reduced aerodynamic drag by 25%, improving fuel economy by 12.5% at highway speeds.

In a related survey of 256 fleets and owner/operators, fewer than 10% were using a trailer aerodynamic device or wide-base single tires. But more than two-thirds of those who used the equipment saw better fuel economy than they originally expected.

Any barriers seem to include installation costs, the downtime associated with damage, weight sensitivities or a lack of service locations.

About two-thirds of those in the survey were worried about a lack of available products, but that has changed.

“Thanks to CARB (California Air Resources Board), many trailer OEMs are now offering skirts and wide-base single tires as a factory installed option,” Golsch says. “We are going to be approaching a number of the trailer OEMs regarding factory-installed boat tails over the next few months.”