Washington, DC, May 06, 2026 (GLOBE NEWSWIRE) — Diesel, gasoline, natural gas, and propane continue to be the primary fuel and technology choices for America’s commercial trucks, transit, and school buses, with the share of advanced technology near-zero emissions diesel vehicles increasing 4% since 2023, according to the Engine Technology Forum (ETF), a not-for-profit educational association.
ETF’s analysis of S&P Global Mobility TIPNet data on U.S. commercial vehicles in operation as of December 2025 found that more than 98% of the nation’s commercial vehicles – from small white box delivery trucks up to the largest 18-wheelers – are powered by internal combustion engines. Diesel makes up the largest share at 76%, followed by gasoline at 23%, then natural gas at 0.5%.
Nearly two-thirds of all diesel transit buses (63%) and nearly three-quarters of all diesel school buses (72%) in operation were powered by advanced diesel engines (model year 2010 and newer) at the end of 2025, increasing 8% and 5%, respectively, since 2023.
As of December 2025, 67% of all commercial diesel vehicles on the road were model year 2010 and newer (MY 2010+), a 6% increase from 2023. From 2020 to 2025, the share of Class 3-8 diesel vehicles in operation that are MY 2010+ increased from about 50% to over two-thirds. These vehicles feature advanced emissions controls that achieve near-zero emissions.
Arizona has the fastest growing population of MY 2010+ Class 8 diesel trucks in operation, with a nearly 23% increase compared to 2023.
“As more of the nation’s truck and bus fleets adopt the latest generation of advanced diesel and natural gas technology, communities are experiencing cleaner air and fleets save on their fuel expenses, too,” said Allen Schaeffer, Executive Director of the Engine Technology Forum. “Previous research showed the significant climate, fuel savings, and clean air impacts in the U.S. of the newer generation (MY 2010+) of advanced diesel in Class 3-8 heavy-duty vehicles. From 2011 through 2030, this generation of diesels will save approximately 1.3 billion tons of carbon dioxide emissions and 130 billion gallons of fuel, while yielding cumulative savings of 1 million tons of particulate matter and 18 million tons of nitrogen oxide. These benefits will be even greater once new emissions regulations are implemented for new vehicles starting in 2027.”
Emerging zero-emissions technologies, including battery electric and fuel cell electric vehicles, presently make up a small fraction of the commercial vehicle fleet. In this analysis, the largest portions of vehicles powered by electricity in the studied population are transit buses (8.6% EV), followed by school buses (1.1% EV).
“As the timing and degree of transition to alternative vehicles and fuels remains in flux, the importance of continued investment in new technology internal combustion engine (ICE) vehicles is vital to ensure continued progress on clean air and energy efficiency. Replacing older vehicles with new advanced ICE technology delivers substantial benefits. It would take more than 60 of the current generation diesels to equal the emissions of a single heavy-duty diesel truck built in the 1990’s,” said Schaeffer.
California leads all states in the adoption of EV technology in commercial trucks, non-school buses (transit and inter-city buses), and school buses. For commercial vehicles (Class 3-8) alone, California accounts for more than 21% of all EVs in operation, followed by Michigan, Florida, Maryland, and Illinois.
Continued improvements in internal combustion engines in the form of even nearer-to-zero emissions are on the horizon. Engine and vehicle manufacturers are working to meet the most recent emissions regulations which begin in 2027. These are expected to reduce nitrogen oxide emissions by over 80% from today’s levels.
“While the scale and speed of alternative fuel adoption by the commercial vehicle sector is uncertain, internal combustion engines demonstrate continuous improvement and are expected to dominate our goods movement and public transport sectors for decades to come. That’s why having more of the newest generation of these vehicles in operation will deliver the greatest benefits for all,” said Schaeffer.
About the Engine Technology Forum
Founded on the principles of fact-based education, science, outreach and collaboration, the Engine Technology Forum is dedicated to promoting a greater understanding of the benefits of advanced engines and the fuels that they use, as well as how these contribute to a sustainable future. Sign up for our digital newsletter and connect with us on LinkedIn, X, Facebook, Instagram, and YouTube.