Fuel use represents up to 39% of a fleet’s cost-per-mile, according to the American Transportation Research Institute. A single commercial truck, running 100,000 miles a year at 7 mpg, can consume up to $70,000 in fuel a year. Couple this with record-high diesel prices, and it’s easy to see why it literally pays to pay attention to how much fuel your trucks consume.
In “Fast Ways to Save Fuel,” the first of a three-part HDT webinar series examining how fleets can better manage fuel costs, panelists explored ways fleets can boost their fuel efficiency in the near term, such as immediate changes to operations, add-on fuel-saving devices, and tweaking engine parameters.
“There are many things fleets can do to save fuel,” said Mike Roeth, executive director of the North American Council for Freight Efficiency. “It is more top of mind when fuel costs more.”
The industry has seen wild swings in fuel costs for more than a decade, according to data from the U.S. Energy Information Administration. Diesel fuel peaked at $4.30 a gallon during the run-up to the Great Recession, plummeted during the COVID-19 pandemic, and as HDT went to press was setting new records of well over $5 a gallon. “But fleet fuel expenses are large even when fuel costs less,” Roeth said. For example, even at $3 a gallon, a fleet may pay over $40,000 in fuel for a single truck that averages 100,000 miles a year.
Gerry Mead, executive vice president of maintenance and equipment for intermodal and logistics company Hub Group, explained that “the worst time to prepare to get better fuel mileage is when fuel costs are high. When the first time you consider saving fuel is when it’s over $5 a gallon, you are being reactive instead of proactive,” he said.
The very first step, Mead said, is to understand your fleet’s particular operational characteristics. “Every fleet operates differently,” he said. With that understanding, you can delve into possible fuel-saving strategies and figure out what works for your fleet.
In 2017, NACFE’s Run on Less demonstration program evaluated what some of the most fuel-efficient fleets and drivers did to save fuel. The fleets averaged 10.1 mpg compared to the industry average of 7 mpg. Roeth said many fleet managers believe the results were due to the vehicle specs. And, in fact, NACFE found that spec’ing choices such as downsped powertrains, automated transmissions and implementing the right axle configuration were important — but there were plenty of strategies that had little to do with truck specs.
NACFE’s research found that better driving, maintenance and tire management played a huge role in those numbers — and those are things you can put into play without waiting to spec your next truck.
Based on NACFE’s evaluation of the first Run on Less and Run on Less Regional in 2019, Roeth recommended several steps fleets can take to cut fuel use immediately.
Educate and incentivize drivers. Run on Less saw some of the most proficient drivers on the road behind the wheel. Hiring, educating, and incentivizing drivers for the best fuel efficiency possible is critical. Roeth recalled one of the drivers, Meijer’s Rita Bare, told him after 2019’s Run on Less Regional, “‘I drive like I’m driving in icy weather every day of the year.’ She’s gentle on the accelerator and careful on braking, because every time you brake, you gotta get this big truck with all the freight up to speed again.”
Slow down. Trucks typically average 70 mph with a full load of freight as they move down the highway. When trucks slow down to 65 mph, Roeth said, “you can improve your mpg by a half mile per gallon. That’s not chicken feed when we’re talking about saving fuel.” Speed limiters, as well as driver education and incentives, can help here.
Reduce idle time. Educate drivers about the effect of idling on fuel economy. Reward them for keeping idle time low. Make sure they have the ability to stay comfortable in their cabs overnight without idling. Use engine settings to automatically turn the engine off after a specified time period.
Slash out-of-route miles. “Work hard to keep out-of-route miles to a minimum, which is easier said than done,” Roeth said. “But it is something to pay attention to.”
Improve maintenance: A well-maintained truck will get better fuel economy. Keep your diesel particulate filter and other filters clean and keep trucks and trailers in alignment. Use lower-viscosity lubricants. Monitor and maintain tire pressure.
“You lose fuel economy with under-inflated tires,” Roeth said. “An easy add-on here would be tire pressure inflation systems or automatic tire inflation on trailer tires.”
Manage your tires: “Don’t replace tires until you need to. Over time, less tread equates to better fuel economy,” Roeth said, because it reduces the rolling resistance of the tires. Webinar panelist Joe Puff, vice president of truck technology and maintenance at NationaLease, agreed. “I’ve seen studies that show there can be up to 6% better fuel efficiency when you run tires down, compared to tires with new tread,” he said. “I don’t want people to think it’s OK to put bald tires on their trucks. But run the full life of the tires and have a solid tire program.”
Accelerate Aero Add-On Adoption
Wind resistance accounts for 65% of fuel consumption, and by altering the aerodynamic profile of trucks and trailers, fleets can lower wind resistance and slash fuel consumption by up to 12%, according to a recent DAT Freight & Analytics blog, “Rising Fuel Prices: A Trucker’s Guide to High Fuel Costs.”
Though the benefits of adding aerodynamic devices are known, especially for trucks that run a lot of on-highway miles, Hub Group’s Mead suggested there are many things to consider. He advised fleets to take six steps:
- Understand your operational characteristics. Length of haul, last-mile deliveries, regional versus long haul, different trucks and trailer types, all affect the effectiveness and choice of aero add-ons.
- Join and consult with industry organizations. Organizations such as NACFE, the ATA’s Technology & Maintenance Council, and others offer information on fuel testing using proper SAE procedures. Some organizations will come out and fuel test member’s fleets, he adds.
- Understand add-on technologies. Not all technologies work for every fleet. Select technologies based on a solid knowledge of how they work and what they do.
- Determine the fuel savings potential for the technologies being introduced. Ask for verified testing results, talk to other fleets, run a test of the devices in your own operations.
- Study and gain knowledge on the future outlook and upcoming regulations. “Information is power,” Mead said. “Knowing what’s coming and what states are adopting” can direct your course.
The choices for aero add-ons are as plentiful as the types of trucks on the road, Mead said. Trailer side skirts have become common since they were mandated by California emissions rules, but there are many other possibilities. For instance, aerodynamic mudflaps can reduce road spray and change air flow.
“If you get the right ones, they have a front and a rear shaped like an airway, so aerodynamics comes into play,” he said.
Roof, chassis and drive wheel fairings also can help — depending on the application.
“If it’s a truck pulling a flatbed trailer, a roof fairing obviously won’t do much,” he says. “If you’re pulling a container, you might change the height of your tires, too, to match trailer and tractor height to save fuel.”
- Consider fifth-wheel settings. “Can you reduce your fifth-wheel position?” he asked. “Can you reduce the gap between the back of the cab to the front of the trailer?” If your fifth wheel setting is as close as it will go, another option is a device to smooth the air flow between the tractor and the trailer. But fleets must consider the importance of closing the gap to their operations. Local delivery, for instance, probably won’t gain a lot of benefit. Evaluate versions that can auto retract. “The choices you make today will affect you tomorrow,” he said.
Tweak Engine Settings
Dialing in basic fuel economy parameters on engine settings, such as vehicle speed settings, idle shutdown times, and predictive cruise control, can save up to 5% in fuel.
In the webinar, NationaLease’s Puff suggested digging deeper into the ECM to save even more. However, he stressed, “It’s important to remember that available parameter options vary considerably by OEM, engine platform, and engine year.”
“Every OEM has their own naming conventions for the technology,” he added. “So what Detroit calls PassSmart, Cummins calls Reserve Speed, for example. It’s also important to note that all the parameter settings in the world cannot compensate for a mis-spec’ed vehicle.”
Puff provided a list of basic parameters that offer fuel efficiency benefits but stressed that fleet owners must work with OEMs to select the right parameters for their operation and equipment.
Road Speed: “The faster a vehicle goes, the more fuel it burns. For every 10 mph over 55 mph, you reduce fuel efficiency by 1 mile per gallon,” Puff said. “So, slowing vehicles down is really key. Parameter settings are available in one mile an hour increments. I like setting road speeds to 66 to 68 miles per hour.”
Cruise Control: “I set cruise control at 2 to 3 mph faster than pedal speed to encourage drivers to use it,” he said. “Small variances in pedal pressure while driving can have a 1% to 3% savings, which is significant.”
PassSmart/Reserve Speed: This parameter sets how many minutes a day drivers can exceed the speed limit. “You might program this parameter to let the driver go 3 mph over the speed limit for 30 minutes per day,” he said.
Adaptive Cruise Control: When enabled, adaptive cruise control allows cruise control to follow the vehicle in front automatically. It slows down or speeds up the vehicle as the vehicle in front changes speed. “This parameter flattens out the peaks and valleys of adjusting your speed,” Puff explained. “Adaptive cruise control can add up to 5% in fuel savings.”
Predictive Cruise/Intelligent Powertrain Management: This setting can increase fuel savings by 3% on top of cruise control and adaptive cruise, Puff said. It integrates GPS and terrain maps to prepare vehicles for the terrain ahead. When enabled, it prepares for curves and hills and sets optimal vehicle efficiency and road speed automatically.
E-Coast/Smart Coast: This parameter disengages the clutch and allows the engine to idle as the truck goes down hill or slows down. It uses the momentum of the vehicle to slow the engine down.
Crest/Dip Coasting: This parameter lets operators set predetermined road speed at the top of the hill or when dip coasting or moving downhill.
Vehicle Acceleration Management: Puff recommended using this parameter to save up to 2% in fuel by reducing excessive RPMs in light loads.
Idle Shutdown: “Quick math: If someone runs 40 hours a week of idle time and they burn 40 gallons of fuel, that’s over $11,000 a year in fuel burned idling,” Puff said. “The more fleets get away from idling, the better.” Fleet owners can set engines to idle for a set time (Puff uses 10 minutes) before they shut down. There are idle shutdown overrides for situations such as high or low ambient temperatures.
Transmission Settings: There are also parameter settings for transmissions. Among these is gear-down protection, which limits the speed for one gear below top gear to encourage drivers to use top gear, lowering engine rpm and reduces fuel consumption by up to 4%. Others include load-based speed control, soft cruise, progressive shifting and torque limits.
There are hundreds of parameters that fleets could tweak to improve their fuel efficiency, Roeth said, “so it can be very daunting. It’s easy to just say, ‘I’m just going to keep what I’ve got. The engine parameter settings I have are not keeping me from delivering freight or hauling concrete or asphalt. So, they just become something you kind of forget about.’”
Mead followed up on that. “Fleets may think, that’s how the truck came, and [the dealer] know what they’re doing. But a lot of times, the sales guys, God bless them, they really don’t. And you have to challenge them to get what you need for your operation. Because typically, they really don’t know it — only you did.”
This article first appeared in the special fuel issue of Heavy Duty Trucking (June 2022).