A decade ago, old-school drivers and fleet managers snickered at concepts such as aerodynamic tractors, trailer boattales, wide-based single tires, and automated manual transmissions. Fuel efficiency tools such as telematics-based driver coaching, 6x2 drivelines, predictive cruise control, economy coast modes, and downsped powertrains were virtually unknown at the time.
Today, all those tools are readily available for fleets focused on fuel economy. And even better: There’s help available today. Lots of it.
Talk to any OEM, industry supplier or dealership, and they will have a host of fuel-saving options and technology on hand to help you drive fuel efficiency up and operating costs down. And there are other organizations dedicated solely to the adaptation and application of fuel-efficient technology and procedures as well.
The North American Council for Freight Efficiency is one such group. It was formed following a 2009 meeting with the Rocky Mountain Institute. Meeting attendees representing a variety of industries determined that an unbiased, comprehensive group would help the trucking industry navigate the large number of energy efficiency technologies and practices available.
Mike Roeth, NACFE’s executive director, has a background in engineering and spent a good chunk of his early career working for a major North American truck OEM. Under his guidance, NACFE works to provide real-world solutions to help fleets boost their fuel economy without degrading operational performance. NAFCE’s goal is clearly focused on efficiency and productivity.
Roeth and his team have been putting out a series of detailed, analytical Confidence Reports on specific fuel economy technologies, concepts, and procedures for almost a decade now. But last year, the group embarked on its most ambitious project yet — the Run On Less Fuel Economy challenge.
Organized by NACFE and Carbon War Room with title sponsors Shell and PepsiCo, the Run on Less challenge was firmly rooted in real world fleet operations. Seven fleets nationally recognized as fuel economy leaders hauled real freight from multiple locations around the United States for three weeks of evaluation runs that culminated at the North American Commercial Vehicle Show in Atlanta last September.
The participating fleets were Albert Transport Inc., PepsiCo’s Frito-Lay division, Hirschbach Transportation, Mesilla Valley Transportation, Nussbaum Transportation, Ploger Transportation, and U.S. Xpress.
“All the trucks involved in the run were equipped with commercially available technologies that are available today. We wanted to have some fun — and find out what’s possible in terms of mpg running current equipment today,” Roeth says. “We went to great pains to make sure that everything on the trucks was validated and fair. There was no sneaking stuff onto the tractors. Suppliers and OEMs weren’t allowed to put prototype or experimental equipment on the trucks. And the trucks ran normal routes in a variety of applications all over the country.”
Once the challenge began, drivers had to make the best of whatever cards they were dealt in the course of normal fleet operations. For example, Joel Morrow, director of research and development for Ploger Transportation, was in the hunt for the lead position in terms of mpg, when bad luck came his way. “I had one of our aerodynamic trailers on one of the runs, when I had to drop it and hook up to this old trailer that was an absolute piece of sh**,” he says, laughing. “I shouldn’t use language like that — but that’s really what this thing was. No aerodynamics at all. The wheels weren’t aligned. And I wasn’t happy about it. But the Run was about real-world trucking. So I had no choice but to deal with it.”
If you’re feeling sorry for Morrow, don’t. He still managed to turn in numbers well over 9 mpg during the three-week event.
“It ended up being the real world in the extreme,” Roeth says. “We dealt with two hurricanes during the run, straight-line winds, highway congestion and — yes — Joel’s trailer. Which we calculated cost him about 1.5 mpg by the end of the challenge. But even with all that going on — which are the conditions that truck fleets and drivers deal with day in and day out — we still managed to achieve a combined average of 10.1 mpg for all the trucks that participated in the Run on Less event. Which proves that these fuel-efficiency technologies and components can deliver big savings for North American fleets out there hauling real freight on real routes with real drivers behind the wheel.”
The good news is there are a lot of fuel economy options on the table, depending on your application. The bad news is that not all of them will deliver big returns. But a fuel-sipping tractor-trailer is really a sum of its parts — and every little tenth of a mile can eventually help pay big dividends over the long haul. Roeth highlights some of the strategies used by the Run on Less participants to reap big gains.
Big gains via the drivetrain
As effective as automated transmissions are in saving fuel, their fuel economy potential increases dramatically once they are combined with downsped transmissions and predictive- and adaptive-cruise control systems.
The concept of a downsped transmission is pretty simple, really: The fewer rpms a diesel engine turns at highway speeds, the less fuel it burns. Of course, the fewer rpms an engine is turning, the less horsepower and torque the driver has to work with in terms of getting a tractor-trailer moving and maintaining cruising speeds. That’s where automated transmissions combined with lower gear ratios come into play.
One disadvantage to a downsped powertrain is increased vibration and associated shock loads to driveline components. Automated transmissions can be programmed to compensate for lower torque and deliver smooth shifts while allowing engine speeds as low as 900 to 1,000 rpms at 65 mph. According to NACFE, this technology can deliver between 3% - 6%, or a half a mile per gallon, boost in fuel economy.
Adaptive and predictive cruise modes take the power of automated transmissions even further. These advanced driving systems use both radar and GPS technologies to keep a tractor-trailer operating as efficiently as possible, regardless of traffic conditions or geography.
Adaptive cruise control keeps a close, electronic “eye” on vehicles in front of the tractor-trailer, and adjusts speeds to compensate as they speed up or slow down. The idea is to keep the driver in cruise mode at all times, and avoid burning fuel unnecessarily as a driver brakes and then applies full throttle to get back up to cruising speed.
Predictive cruise control uses real-time vehicle data combined with GPS information to “look” and “plan” ahead and set gear shifts and throttle inputs in preparation for grades — including terrain beyond a driver’s line of sight. This allows the automated transmission to add just the right amount of throttle to climb a hill with optimal fuel efficiency, then coast down the hill in neutral for maximum fuel economy, and maintain cruise speed once gravity’s “free ride” is over. Some advanced models, such as Volvo’s I-See option for its I-Shift AMT, can actually “learn” a route as it runs it multiple times in order to constantly improve its fuel economy performance until it can run the route as efficiently as possible.
Find out if 6x2s are for you
One of the more controversial, yet beneficial specs NACFE has embraced are 6x2 drive axles, which can deliver an impressive 2% to 3% in fuel economy savings, but come at the cost of an additional drive axle. This has made drivers wary, as stories abound about 6x2 axles getting stuck on snow, ice or even gravel, although Brent Nussbaum, CEO at Nussbaum Transportation, says driver training quickly overcame those shortcomings.
“We train our drivers to handle 6x2 axles and don’t have much of an issue with them today,” he says. “There are also several automatic control systems available from OEMs that can shift weight to the drive wheels to help out if traction is poor.”
Kill off idle time
Nothing degrades fuel economy like an idling truck. Simply coaching drivers to shut down is standard procedure for fuel-focused fleets, with more tech-savvy carriers using vehicle telematics to track idle time and programing engines to shut down automatically at preset time intervals.
Auxiliary power units, which use small diesel motors or stored electric power to heat, cool, and power cabs when an engine is off, are another common fuel economy option, although Roeth notes that their use has leveled off or even decreased in the past several years — for reasons he is not yet able to explain.
Still, idle reduction strategies are a powerful tool for any fleet, which is why Roeth recommends finding out your fleet average for idle times, then looking for ways to cut into that number. “I’ve seen fleets with trucks idling 49% of the time eventually get down to 25% or less,” he says. “And that makes for huge savings in fuel costs.”
Lower your rolling resistance
A final must-have for any fuel-focused fleet, Roeth says, are low-rolling-resistance tires, which use advanced compounding materials to increase tire life and compensate for significantly reduced tread depths.
“Low-rolling-resistance tires — both wide-based and duals — save more fuel than most people realize,” Roeth says. “Typical savings can range from 14 to 28 cents a mile in fuel costs, which is significant.” However, Roeth cautions, LRR tires are more expensive to purchase, and the lowest-profile tires will not work in all fleet applications.
Taken as a whole, Roeth says Run on Less is good news for truck fleets worried about pump prices. “What we demonstrated is that 10 mpg for tractor-trailers is achievable in real world trucking operations,” he says. “It takes a change in culture, and the willingness to experiment and validate new systems and technologies. But the savings realized are significant.”
Related: Building a Culture of Fuel Economy