From Source to Highway: The Messy Middle Emissions Report

August 31, 2026

Print This Article Share it With Friends

(North American Council for Freight Efficiency) Vehicle emissions are an exceptionally broad and complex subject when it comes to understanding the contribution North American freight movement has on the environment and the people who inhabit it. Emissions are one of the things NACFE tracked during Run on Less – Messy Middle.

From Source to Highway: The Messy Middle Emissions Report looks at transportation emissions including carbon dioxide, methane, nitrogen oxides, sulfur oxides and particulate matter of trucks operating with a variety of powertrains including diesel, natural gas, battery electric and hydrogen fuel cell across various regions in North America Each of these powertrain options has different characteristics from an emissions standpoint.

NACFE’s mission is to help fleets invest in cost saving technologies that improve efficiency and reduce emissions. Taken together the three reports from Run on Less – Messy Middle on operations, total cost of ownership and emissions have brought clarity to long-haul. Using the three reports together should give fleet managers a clear path for making decisions on which efficiency technologies are best suited for their operation.

Fleet Group #1: Diesel

As the North American commercial transportation sector navigates the transition toward a decarbonized future the role of the internal combustion engine remains a subject of intense scrutiny and rigorous innovation. However, using advanced filters and chemical treatments in the exhaust, manufacturers have reduced these pollutants by more than 96%. Soon it will take approximately 100 trucks built to 2027 standards to equal the pollution of just one truck from the 1990s.

The Run on Less – Messy Middle diesel group participants have provided a rebuttal to the notion that the internal combustion engine is obsolete. Through the data provided by Albert Transport, Frito-Lay, MVT, and Schneider, NACFE observed a technology that is mature yet capable of radical improvement. Whether through the aerodynamic rigor of MVT, the biogenic fuel adoption of Frito-Lay, the craftsmanship of Albert Transport, or the balanced approach of Schneider, these fleets demonstrate that the Messy Middle is not a waiting room for the future — it is an active construction site for a cleaner present.

Fleet Group #2: Natural Gas

Natural gas vehicles, using CNG or liquefied natural gas (LNG), offer a distinct emissions profile defined by the properties of methane. Natural gas is a fuel with the potential to help reduce total GHG emissions with significant advantage in reducing the more immediate and local health effects caused by air pollutants like NOx and PM.

The net CO₂ benefit of a natural gas engine is in the range of 13% to 18% compared to diesel fuel. Natural gas produces approximately 27% less CO₂ per unit of energy on a fuel-comparison basis compared with No. 2 diesel fuel. However, the natural gas engine is less efficient than a diesel, and natural gas must be compressed for storage on the vehicle.

The Cummins X15N (natural gas) represents a paradigm shift from the traditional diesel architecture, despite being part of the same HELM fuel-agnostic platform. While it shares many components below the head gasket with the X15 diesel, its combustion strategy and aftertreatment are fundamentally different.

In the Messy Middle, the natural gas group demonstrated that fleets do not need to wait for a BEV breakthrough to make massive strides in sustainability. The hardware is ready, the fuel is potent, and as these three fleets have proven, the natural gas truck is ready to work.

Fleet Group #3: Battery Electric Vehicles

Tailpipe, or tank-to-wheel, emissions from a BEV in operation are virtually zero. The vehicle propulsion system emits no NOx, PM, or CO₂ during operation, providing immediate air quality benefits in local operating environments. Therefore, discussions about BEV emissions must revolve around the well-to-tank supply of energy to the vehicle batteries.

The data confirms that in 2025, battery-electric trucks are no longer experimental curiosities but rather are capable workhorses. With efficiencies ranging from 1.6 to 1.9 kWh/mile, these vehicles are converting energy into motion at a rate three to four times more efficient than diesel engines. Environmentally, the impact is profound — achieving GHG reductions of 62% to 99% depending on the grid and eliminating local criteria pollutants entirely.

Fleet Group #4: Hydrogen Fuel Cell Vehicles

Hydrogen fuel cell vehicles (FCEV) ideally emit only water vapor and warm air. The chemical reaction taking place inside the fuel cell is remarkably clean compared to an internal combustion engine.

The participants of Run on Less – Messy Middle confirm FCEVs have the potential to successfully navigate today’s Messy Middle. The two FCEV’s in the Run demonstrated when the vehicle technology is paired with a developing fuel supply chain — whether centralized like Pilot’s or modular like OneH2’s — the result has the potential to be a viable, scalable, and zero-emission replacement for the heavy-duty diesel truck. The question is no longer if the technology works, but how fast the infrastructure and vehicles can mature to meet it.

Comparative Analysis: Navigating the Messy Middle

As fleet operators evaluate their options for decarbonization, they are faced with a matrix of choices: clean diesel, fossil diesel, RNG, BEV, and FCEV. Each has a distinct health impact profile when analyzed from a lifecycle perspective.

RNG represents a unique opportunity to decouple heavy-duty trucking from the challenges of diesel. From a criteria pollutant standpoint, modern natural gas engines are inherently cleaner than diesel. The battery-electric truck is the gold standard for local health. With zero tailpipe emissions, a BEV eliminates street-level NOx, PM, and VOCs entirely. FCEVs offer a middle ground. Like BEVs, they have zero tailpipe emissions (emitting only water vapor). Their health impact is entirely determined by the production method of the hydrogen.

Key Findings

The study team identified key findings impacting the transition of the North American heavy-duty trucking industry.

Fuel/Energy Origin Outweigh Engine/Powertrain Technology: The carbon footprint of a truck is determined more by the origin of the fuel molecule than the metal of the engine block.
Alternative Fuels Achieve Diesel-Like Performance: The era of yesterday’s underpowered alternative energy truck is over.
Decarbonization as a Public Health Need: The health impact from freight emissions are large and unevenly distributed. Reducing emissions in populated freight corridors leads to significant reductions in negative health outcomes and healthcare cost expenditures.
The Driver Impact: Drivers have as significant an impact on fuel economy and emissions reductions as do the truck technologies.
Fleets Should Include Emissions Considerations in their Decisions: As fleets look to the many options available when considering their next truck purchases, it is important to include emissions considerations along with operational and total cost of ownership in decision making.

READ MORE

Related articles

Terrain, Technology, and Telematics: The Messy Middle Operations Report (North American Council for Freight Efficiency)
Forecasting the TCO of Powertrain Alternatives: The Messy Middle Cost Report (North American Council for Freight Efficiency)

Excerpt from North American Council for Freight Efficiency Operations Report: The Terrain, Technology, and Telematics: The Messy Middle Operations Report covers operational factors of Run on Less – Messy Middle including detailed specs of each truck, operating characteristics and focuses on the impact of speed, terrain and elevation on the freight efficiency of each truck.

...

Run on Less – Messy Middle confirmed that freight decarbonization is not a simple technology swap but rather a complex, multi-decade transition requiring operational adaptation, infrastructure development, and technology-specific deployment strategies. The 13 fleets and 14 trucks demonstrated that each powertrain technology has a legitimate operational envelope where it can deliver competitive performance today — and equally, boundaries beyond which it struggles to match conventional operations.

After analyzing the data, the study team came to the following conclusions.

Diesel remains the operational benchmark. The diesel fleets achieved efficiency levels nearly double the typical long-haul fleet average — up to 11.8 MPG compared to approximately 6 MPG — while maintaining 500 to 800+ mile daily productivity across varied terrain. This performance, combined with ubiquitous infrastructure, establishes context for evaluating alternative powertrains. Renewable diesel provides a near-term decarbonization option (50% to 80% carbon intensity reduction) using existing assets and infrastructure.
Terrain is the most significant performance variable. Diesel demonstrated terrain resilience with approximately 30% efficiency variation between flat corridors and mountain passes. BEVs showed greater sensitivity, with efficiency variations of 50% to 70% across comparable terrain differences, translating directly to range variation. Route-specific terrain analysis is essential before deployment decisions.
CNG/RNG serves specific duty cycles well. The Cummins X15N natural gas engine demonstrated diesel-competitive pulling power across demanding applications including heavy-haul tanker and triple-trailer configurations. CNG/RNG efficiency favors highway-dominant duty cycles with predictable infrastructure access. RNG sourced from organic waste can achieve carbon-negative operations.
BEV technology is expanding beyond regional applications. Battery-electric trucks with 565 to 705+ kWh battery packs achieved 350 to 500+ mile daily operations, with an 875-mile validated single-day maximum on favorable terrain. Terrain sensitivity, charging infrastructure requirements, and payload constraints require corridor-specific evaluation before deployment.
Hydrogen fuel cells demonstrated operational characteristics but face significant barriers. Fuel cell trucks showed quick refueling and weight advantages over BEVs. However, infrastructure scarcity, high fuel costs, and energy pathway efficiency concerns present substantial challenges for commercial-scale deployment.
Real-world operational data complements specifications. Across all technologies, actual operational performance varied based on terrain, duty cycle, payload, and driver behavior. Specification sheets provide important baseline information; validated operational data helps fleet operators understand performance in specific applications and set realistic expectations.
Daily productivity matters as much as efficiency. Technology suitability depends not only on energy efficiency but on daily mileage capability — the ability to complete freight assignments within hours-of-service windows.
Infrastructure availability shapes deployment options. Charging and hydrogen refueling networks are developing unevenly across regions. Successful deployments require alignment between vehicle needs and infrastructure positioning along freight corridors.
Human factors influence outcomes across all technologies. Efficiency outcomes are shaped by driver training, performance incentives, maintenance discipline, and dispatch strategy. The highest-performing fleets in the Run demonstrated comprehensive operational optimization alongside technology selection.
Fleet strategy benefits from portfolio thinking. Many fleets will operate multiple powertrain technologies in the near- to mid-term, matching each to appropriate applications based on duty cycle, infrastructure access, and operational requirements.
Organizational culture influences technology success. Fleets that approach technology transitions with commitment and adaptability — from leadership to drivers and technicians — demonstrated stronger outcomes in Run on Less – Messy Middle. READ MORE

Excerpt from North American Council for Freight Efficiency Cost Report: The Forecasting the TCO of Powertrain Alternatives: The Messy Middle Cost Report is designed to guide fleet owners through the financial realities of transitioning to alternative powertrains by analyzing the Total Cost of Ownership (TCO) across all four powertrains. The report focuses solely on Class 8 vehicles, forecasts out to 2035, accounts for duty cycles and utilization and highlights the variables that matter when determining TCO. Critically, the analysis assumes zero incentives in its TCO calculations. This provides a worst-case scenario that reveals when parity occurs organically through technology improvements and operational savings.

...

TCO must be a bespoke calculation for each fleet. Highly variable factors — such as hyper-local electricity rates, fleet-specific infrastructure strategies, and negotiated vehicle prices — mean that a national average will rarely reflect a specific fleet’s actual balance sheet.

Each powertrain option has its strengths and weaknesses.

Diesel: Diesel remains the incumbent benchmark across all duty cycles, but its long-term cost advantage is eroding.
CNG/RNG: Compressed natural gas remains a stable middle ground, providing a lower TCO than diesel in the 2028 and 2035 timeframes.
BEVs: Battery-electric vehicles show the most aggressive TCO improvement of any technology. BEVs move from being one of the more expensive options in 2025 to becoming the definitive market leader in regional cycles by 2035.
FCEV: While hydrogen vehicle and fuel costs are projected to drop significantly over the next decade, FCEVs remain the most expensive powertrain across almost all duty cycles in NACFE’s 2035 modeling.

There are some key findings about powertrains based on duty cycle.

Long-Haul Over-the-road: Diesel remains the cost leader through 2028, but BEVs achieve parity and narrowly win the segment by 2035.
Regional Linehaul: This duty cycle represents the primary shift in the model. By 2035, BEVs will transition from being twice as expensive as diesel today to becoming the most cost-effective powertrain overall.
Regional Return-to-base: RTB represents the strongest economic case for electrification. By 2035, BEVs will provide a 12% TCO advantage over diesel.
Urban/Metro Pickup & Delivery: In 2025, ZEVs are severely penalized by low utilization; however, by 2035 the projected drop in vehicle prices and maintenance savings allow BEVs to finally undercut diesel organically.
Drayage/Port Shuttles: This sector follows a trajectory similar to RTB, showing very high potential for BEV adoption, with the BEV TCO projected to drop by nearly 50% over the next decade.

...

Fleets must start by estimating all the component costs of the vehicle over its lifetime. Fleets must then combine and boil these costs down into the one metric that matters most to the bottom line: Total Cost of Ownership Per Mile ($/mi).

The basic math looks like this:

TCO Per Mile ($/mi) = [Total Capital Costs + Total Operating Costs] ÷ Total Lifetime Miles

To further break this down into the specific components discussed in this report, the equation looks like this:

TCO Per Mile ($/mi)
=
[Total CapEx (Vehicle Cost – Residual Value + Charging & Fueling Infrastructure – Incentives & Grants + Financing Fees)
+
Total OpEx (Fuel & Electricity + Maintenance & Repair + Insurance + Regulatory Penalties)]
÷
Total Lifetime Miles

There is no universal TCO. Fleet managers must do the work to construct a TCO analysis that is tailored to their fleet-specific routes and costs. Before making a procurement decision, fleets should conduct a custom TCO analysis rather than relying solely on general national averages. Factors to consider include fleet performance baseline, utility and fuel contracts, available incentives, and organizational financial specs.

A step-by-step process fleets can use to analyze which powertrains make sense in their various duty cycles should include the following: establish a true diesel cost baseline, map high-opportunity geographies, match the powertrain to the duty cycle, gather real-world quotes and build the equation, determine residual value assumptions, assess total operating economy, estimate a parity point and stress-test the parity window.

Study conclusions include the following:

TCO Is Bespoke, Not Universal: There is no single date when parity is achieved. Parity is an operational window defined by a fleet’s specific geography, duty cycle, and costs.
BEVs Are the Long-Term Economic Winners: Driven by a projected 45% drop in vehicle purchase prices and superior energy efficiency, BEVs achieve the lowest Net TCO across all modeled duty cycles by 2035.
Return-to-Base and Drayage Are BEV “Goldilocks” Lanes: Regional RTB and drayage cycles offer the strongest immediate case for electrification, benefiting from high mileage routes and predictable depot charging.
Diesel’s Financial Advantage Is Finite: The era of diesel as the undisputed low-cost leader is ending. Rising costs for emissions compliance, specialized maintenance, fuel price shocks, and insurance are creating a diesel cost escalator that eventually will push its Net TCO above zero-emission alternatives in every duty cycle.
CNG/RNG Is the Near-Term Hedge: For fleets seeking a pragmatic, infrastructure-ready exit ramp from rising diesel costs, CNG/RNG offers the most mature alternative. While eventually overtaken by BEVs on a pure per-mile basis, its ability to match diesel performance in long-haul and weight-sensitive lanes makes it a useful bridge in the Messy Middle.
FCEV’s Niche Is Defined by Speed and Payload: While currently the most expensive option, FCEVs represent a possible choice for high-VMT, heavy-haul OTR lanes where payload capacity and rapid fueling are non-negotiable. READ MORE