Getty Images photo of a Class 8 truck on a highway at sunrise/sunset


Diesel engines power 76% of all commercial trucks, helping move almost 70% of the nation's freight tonnage. While diesel is expected to continue to dominate the trucking sector for decades to come, alternatives to diesel such as battery electric and hydrogen/fuel cells are emerging.

  • 76 %

    Diesel engines power 76% of all commercial trucks

  • 70 %

    Diesel engines move almost 70% of the nation's freight tonnage.

The trucking industry provides an essential service, delivering everything from industrial products and building materials to consumer products, household goods and groceries. More than 15 million commercial vehicles are registered in the US, and 76% are powered by diesel engines. These trucks are the tools of the 711,000 trucking companies and operated by about 3.5 million drivers to deliver freight for the US economy. Of the largest highway tractor-trailer size (Class 8) trucks 97% of are powered by diesel. Of the smaller and medium duty commercial trucks, three out of four are powered by diesel.

Since the late 1960’s, diesel has been the technology of choice for commercial trucks because of its unique combination of features including high power density, energy-efficiency, high-uptime and reliability, million-mile durability, driving range, payload carrying capacity, global parts, servicing and fueling networks, high resale value, compatibility with low carbon renewable biodiesel fuels, and dramatically lower emissions. 

Over the last 20 years, emissions from new heavy-duty diesel trucks, buses, were reduced by 95% for nitrogen oxides (NOx), an ozone precursor, and 90% for particulate emissions. Today’s trucks are so low in emissions that it would take 60 new trucks to generate the same emissions as a single truck manufactured in 1988!

Advanced Diesel Truck Engines Achieve Lower Emissions and are More Fuel Efficient

The newest generation of advanced diesel vehicles makes up a growing portion of the total diesel commercial truck population. In 2021, more than half of all diesel commercial vehicles on the road in the United States were the newest generation equipped with the advanced diesel engines in 2011 and later model years. These trucks have near zero emissions of NOx and particulate matter.

While making commercial trucks much lower in emissions, diesel engine and truck manufacturers have also made them increasingly more fuel-efficient. Since 2011, new diesel commercial trucks realize an average 5% improvement in fuel economy, thanks to advanced emissions controls (selective catalytic reduction) than have enabled optimized engine design toward greater fuel efficiency. This translates into petroleum reduction equivalent to 5.8 billion barrels of crude oil.

An owner of a single new Class 8 truck powered by the latest advanced diesel engine can expect to save about 2,200 gallons of fuel each year compared to previous generations of technology. This reduces greenhouse gas emissions by nearly 30 tons. 

New diesel vehicles continue to increase their penetration in the marketplace in part, due to fuel efficiency requirements of Phase 1 of the U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) Fuel Efficiency standards that went into effect in 2014 and the more stringent Phase 2  rules that started in 2021. The Phase 2 rule is expected to eliminate over 1 billion tons of greenhouse gas emissions from new trucks between 2021 and 2027. More efficient diesel trucks will deliver the overwhelming majority of these benefits even as zero-emissions technologies are expected to gain some market share during the lifetime of the rule.

While diesel trucks are becoming more efficient, diesel is also becoming much lower in emissions with new trucks (2011 and later model year) achieving near zero emissions. Truck and engine manufacturers and stakeholders are developing near-zero emissions solutions for oxides of nitrogen and fine particles. They’re working in support of future standards with the U.S. Environmental Protection Agency through the Cleaner Trucks Initiative

For additional information about engine certification standards and government regulations, visit the Truck & Engine Manufacturers Association (EMA) website.

Potential for Other Fuels and Technologies for Commercial Trucks: Battery Electric and Hydrogen

Interest is growing in alternatives to diesel fuel – such as battery electric and hydrogen fuel cells, even as diesel engines are projected to remain the majority technology for commercial vehicles well into the future.

The Fuels Institute predicts that diesel will remain the standard powertrain and fuel powering commercial vehicles in the future. 

Interest in alternatives to diesel for commercial trucks are driven by several factors including a focus on decarbonizing the goods movement sector to achieve greenhouse gas emissions reductions and to meet net zero carbon global climate change goals.

The potential for lower fuel prices and lower total cost of ownership are also of interest to trucking fleets. Substantial challenges remain in establishing nationwide fueling infrastructure for both hydrogen and battery electric vehicles.