Decarbonization still messy but manageable, NACFE real-world data proves

The transition to zero-emission commercial vehicles remains complicated, even as diesel continues to gain efficiency. The trucking industry is firmly entrenched in a multi-decade transitional era where diesel, natural gas, battery-electric, and hydrogen powertrains will have to coexist in this “Messy Middle.”

That was the central finding of the North American Council for Freight Efficiency’s (NACFE) latest study, Run on Less—Messy Middle. Last September, NACFE tracked 14 Class 8 tractors across 13 fleets. Over 18 days, those vehicles logged 73,000 miles in real-world freight operations. Those tractors spanned the spectrum of power technologies—from optimized diesel to early hydrogen powertrains. 

"The Messy Middle isn't about finding one winning fuel; it's about finding the winning technology for every specific route," Dean Bushey, NACFE's director of programs and lead author of the report, said. "Our data shows that when the powertrain matches the duty cycle, the transition to sustainability becomes both operational and profitable."

Diesel baseline: Pushing the envelope

Diesel fuel remains the undeniable benchmark for operational flexibility, daily productivity, and infrastructure independence. The four diesel fleets in the Messy Middle study—Albert Transportation, Frito-Lay, Mesilla Valley Transportation (MVT), and Schneider—achieved fuel economy ranging from 9 to an astonishing 11.8 mpg.

The national average for diesel tractors has improved from 6 to 7 mpg over the past 15 years, Roeth noted. “We don’t have a lot of the EGR (Exhaust Gas Recirculation) trucks that were bad for fuel economy—they’re now out of the system,” he said.

While the diesel baseline is improving, the Run on Less study shows there is still massive potential for optimization. “Two of these four trucks did 11.5,” he emphasized, pointing out that “we have a lot of fuel economy we can still get out of them” by continuing to work with drivers and adopt new technologies.

Another important point is that the renewable diesel used by these fleets helps decarbonize operations, resulting in a 50% to 80% reduction in carbon intensity without operational changes.

CNG/RNG: The mature bridge

Compressed natural gas (CNG) and renewable natural gas (RNG) proved to be a highly capable pathway for demanding trucking applications. Three fleets—Kleysen Group, UPS, and Wegmans—operated 15-liter natural gas powertrains, putting the Cummins X15N engine to the test.

The natural gas trucks achieved 4.5 to 6.7 mpge (miles per gallon equivalent), running 400 to 700 miles per day. Fleets using RNG sourced from organic waste can achieve carbon-negative operations. Roeth highlighted this environmental benefit as a significant win for the industry.

“Renewable natural gas is really a thing,” he said, noting that a majority of the natural gas powering trucks today is RNG. “When you grab methane that’s leaving landfills, dairy farms, etc., and use that in the truck, that’s a really good thing.”

Battery electric: Expanding beyond regional

Battery-electric vehicles (BEVs) are pushing beyond their regional boundaries. The four BEV deployments—Joyride Logistics, Nevoya, Saia, and 4Gen Logistics—in the 2025 Run on Less were equipped with battery capacities ranging from 438 kWh to more than 900 kWh.

The results were eye-opening for NACFE researchers: BEVs achieved 350 to 500-plus miles daily. JoyRide Logistics pushed the envelope even further, achieving a validated maximum of 875 miles in one day using a Windrose Technologies sleeper. 

Despite current bottlenecks in the charging infrastructure, NACFE remains optimistic about the technology's trajectory. “The battery-electric trucks are getting better and coming quickly, in our opinion,” Roeth said. However, fleets must still proceed cautiously with routing, as terrain dictates BEV suitability and efficiency swings translate directly into range volatility.

Hydrogen fuel cell: High potential, high barriers

Hydrogen fuel cell vehicles (FCEVs) demonstrate distinct operational promise. Penske and Pilot operated Hyundai Xcient fuel cell tractors, achieving a stable efficiency of 7.7 to 7.8 miles per kilogram, operating 120 to 430 miles daily. FCEVs boast a clear weight advantage and faster fueling times than BEVs, whose heavier batteries take longer to recharge than hydrogen tanks. 

Despite the improved technical capabilities, infrastructure remains a prohibitive bottleneck. NACFE’s near-term hydrogen viability remains guarded. 

“I’ll be really blunt. Hydrogen is the fuel of the future—no matter where you are, whether it's 50 years ago or 50 years from now,” Roeth noted. “It seems really challenging … the promise of hydrogen, I would say, still eludes us.”

Until hydrogen fueling station density increases and fuel costs normalize, NACFE expects hydrogen to remain at the demonstration stage.