Just a decade ago, owner-operator Henry Albert of Larado, TX, said he was just hoping to reach 8 miles per gallon. Today, thanks to finely tuned aerodynamics and engine parameters, Albert averages 9.4 mpg and often tops 10 mpg.
“The more you can prevent air from going into places, the better,” Albert said. “With all the battles that we have to fight in this industry, do we really want to pick a fight with the air?”
While Albert is fortunate enough to run a newer tractor-trailer, there are no shortages of affordable aerodynamic products on the market that can transform the performance of older trucks, said Joel Morrow, who runs Ploger Transportation, a fleet in Norwalk, OH, with 62 tractors and 104 trailers.
“If you’re going to drive long haul and you have a dedicated run, put every aerodynamic device known to man on that truck,” said Morrow, whose fleet obtains fuel savings from cab extenders and low viscosity oil.
The 2018 version of the annual fleet fuel economy study by the North American Council on Freight Efficiency (NACFE) found that the overall adoption rate for the technologies studied has grown from 17% in 2003 to 44% in 2017.
As a result, the average fleet-wide fuel economy of the trucks in the study was 7.28 mpg in 2017, up from 7.14 in 2016.
NAFCE said the fleets in the study had adopted between 26% and 61% of 85 possible technologies considered for tractors or trailers. The group noted that no fleet could adopt all 85 on a single tractor-trailer because some are competing solutions.
Among the solutions seeing the most growth included cab extenders, lower viscosity engine oil, and direct drive transmissions.
Among options seeing lower adoption rates, but still widely used to boost fuel economy, were limiting speed, tractor chassis skirts, and wide-based tires.
One increasingly popular choice for fuel economy gains is FlowBelow, whose wheel covers (listed at $450) have practically become the industry standard. They pair with tandem fairings to form its patented AeroKit (listed at $1,800).
NACFE has documented savings of between 1.5% and 2% with the AeroKit. FlowBelow President Josh Butler said customers save 2.25% on average.
“If you’re running in open areas with higher speeds and catching a lot of broadside wind, it probably makes sense,” Morrow said. While there is less benefit with congestion, “wheel covers are a no-brainer. They’re filling big holes in the cavities in the wheels.”
Morow said Schneider has documented 1% truck savings and 1% trailer savings with wheel covers.
Fleets are also finding savings from customized engine parameters on newer trucks, which are virtually cost-free. Jim Nachtman, marketing director for Navistar’s heavy duty product segment, said that adding predictive cruise control, speed limiting, and idle limitations can deliver 3 to 5% savings in fuel economy.
Roy Horton, Mack’s director of product strategy, noted that converting a base model truck to one with premier aerodynamic and powertrain systems can provide $4,000 in annual savings.
Albert’s top-of-the-line truck comes with Freightliner’s Intelligent Powertrain Management system, which “mimics what I would do with the throttle pedal myself. It’s reading the terrain a good mile ahead of the truck and determining how to traverse it while using the least amount of fuel.”
Husted said that down-speeding engines is “the big step forward” for fleets seeking to improve fuel economy.
“We’re in the low 200s when it comes to rear-end ratios,” said Husted. “When I started we were at 411. I never thought that you would be able to create enough power, enough torque to pull a heavy load up a hill with such a low rear end ratio.”
In looking at the trailer, Austin Duncanson, a product engineer at Stemco, said the average unit is kept from seven to 10 years, so it is cost-effective to add tails and other aerodynamic equipment.
“Tails stabilize the trailer so there’s a lot less motion and the fatigue of having to turn the wheel a bunch is reduced substantially, especially in windy conditions,” Duncanson said. “And because of the fuel savings, drivers have to fuel up less. They can get two more hours out of a tank of [diesel] than before. That really adds up on a monthly basis.”
A new option is Rocketail, which has exhibited a certified fuel efficiency improvement of over 3.58 gallons per 1,000 miles. It features an advanced aerodynamic wing design, extending only 12 inches from the rear of the trailer. The wings are always deployed using industrial-grade cable hinges that lock the wings.
Morrow said Ploger trailers feature Wabash’s drag reduction system with “belly” skirts, tails, and nose cones as well as liftable axles. With a 10-year duty cycle, Morrow said that the estimated $6,500 investment is returned in less than two years while delivering 1.2 miles per gallon in improved fuel economy.
Similarly, Jimmy Ray, co-owner of Mesilla Valley Transportation, said Stemco’s boat tails return the $1,200 cost after 100,000 miles.
“We’ve tested all kinds of things and as far as efficiency, they’re the best,” said Ray, whose fleet averages just below 9 mpg.
Hjalmar Van Raemdonck, manager of aerodynamics for Wabco, said skirts are “the no-brainer” among trailer aero products.
“The return on investment comes between 30,000 and 40,000 miles and the fuel savings are more than 5%,” Van Raemdonck said. “If you want to go to the next level, get tails. The return on investment is between 80,000 and 100,000 miles and the fuel savings are about 4%. The next step is a nose [cone]. That takes you to 10%. We only see that with customers who are really into fuel savings since the ROI is at about 140,000 miles.”
Tire monitoring and inflation systems, such as those made by Aperia, Stemco, and Hendrickson, have also proven valuable, as have low-rolling resistance tires. NACFE Executive Director Mike Roeth said tire inflation systems should be installed on almost all trailers because underinflation is so rampant.
“We’ve heard from fleets that one roadside tire-disabling event a year per truck pays for the tire inflation system or tire monitoring system,” said Roeth.
Aperia’s Halo inflation system costs about $1,000 and can be bolted onto a wheel end in less than 10 minutes.
“Tire pressure, tire inflation is very difficult to manage manually,” said Judith Monte, Aperia’s vice president of marketing. “We had a Pitt Ohio study done a few years back and they quantified about $2,400 in savings across the tractor and trailer.”
Garner’s Husted said adding Halo was “the most significant” fuel economy step that his fleet has taken in recent years.
“Halo has helped a great deal because even with a slow leak, it will keep the tire inflated until you get the truck back to the shop. And it doesn’t allow the abnormal wear pattern to start,” he said.
The company’s 87 tractors average about 7.4 miles per gallon.
Stemco’s Aeris tire inflation system comes in mechanical and smart sense versions. Lee Alexander, Stemco’s director of product management, said that customers are just evenly divided on which one they prefer, in part because the smart sense version costs only $100 more.
“The mechanical one is a basic system that will tell you that you’ve got a problem with a wheel end,” Alexander said. “The smart sense version gives you an indication of which wheel end is taking air.”
Many fleets like Mesilla Valley are more proactive. Ray, who uses Stemco’s smart sense system, said that his average tire costs $1,000.
“If the tire will hold air, the pressure system will get you to the delivery point, but the monitor system will save you money because you’ll never run a low tire,” Ray said. “Say I want to know about any tire that’s at less than 60 pounds. If I can tell that a tire is losing five pounds a day and has been sitting for 20 days, do I call emergency road service and spend $500-$600 or do I call the driver and tell him that I’ll let him know when to go? That’s managing the system from afar and saving a ton of money.”
And then there are the savings that come from ingenuity and cost nothing: closing the gap between the truck and the trailer, which Morrow said should be between 39 and 44 inches.
“For every 10 inches, they say it’s three-quarters of a percent loss,” Morrow said. “I’ve had trucks come in here dealer-spec’d that have had 60- or 65-inch gaps. That’s free money right there. Overall, if you do everything right with your truck and your trailer, you can probably improve your fuel economy 11-11.5 percent.”