More than one-third of all medium and heavy duty commercial trucks registered in the United States are now equipped with newer technology clean diesel engines.
Clean Diesels Claim 33% of On-Highway Market
Since the first clean diesel engines were introduced more than seven years ago, they now represent about one-third of all the trucks registered to operate on U.S. highways. The total population of in-service clean diesel engines now numbers about 2.8 million.


According to new data compiled by IHS Automotive for the Diesel Technology Forum, 2.9 million of the nation's 8.8 million trucks are now powered clean diesels.
“Because more than 95% of all heavy-duty trucks are diesel-powered it is significant that more than one-third of these trucks are near-zero emission vehicles,” says Allen Schaeffer, executive director of the Diesel Technology Forum. “Diesel trucks are literally the driving force behind goods movement in the U.S. and worldwide economies, so the fact that the clean diesel fleet is increasing is good news for improved fuel efficiency and the environment. These new trucks are so clean that it now takes more than 60 of today’s clean diesel trucks to equal the emissions from a single 1988 truck."
The new data includes total registration information on Class 3-8 trucks from 2007 through 2013 in all 50 states and the District of Columbia.
The Top 5 states for 2007 or newer diesels by vehicle population are Indiana (50.4%), Utah (44.8%), Oklahoma (41.9%), Texas (41.9%) and Wyoming (41.4%).
The Top 5 states for 2010 or newer diesels by vehicle population are Indiana (28.7%), Oklahoma (26.6%), Utah (23.4%), Texas (20.7%) and Nebraska (20.5%).
The new clean diesel technology has reduced emissions from heavy-duty diesel trucks and buses by 99% for nitrogen oxides (NOx) and 98% for particulate emissions (PM).
Beginning in 2007, all heavy duty diesel trucks sold had to meet particulate emissions levels of no more than 0.01 grams per brake horse-power hour (g/HP-hr).
“Last year was the fifth consecutive year of increased penetration of the new clean diesel trucks in the fleet, reflecting the continuing confidence that American truckers have in the performance and fuel efficiency improvements of new technology diesel engines,” Schaeffer adds.
The Diesel Technology Forum has more information about clean diesel trucks.
More Fuel Smarts

Vanair Introduces Solar, Battery Power Ecosystem for Class 8 Trucks
The company’s expanded EPEQ ecosystem includes flexible solar panels, lithium batteries, hydraulic power systems, and a portable fast charger for electric trucks.
Read More →
Run on Less “Messy Middle” Data Shows Multiple Paths for Truck Powertrains [Listen]
Listen as Mike Roeth of the North American Council for Freight Efficiency shares insights into battery-electric trucks, natural gas, biofuels, and clean diesel on this episode of HDT Talks Trucking.
Read More →
Run on Less “Messy Middle” Data Shows Multiple Paths Forward for Truck Powertrains [Watch]
NACFE's Run on Less - Messy Middle project demonstrates the power of data in helping to guide the future of alternative fuels and powertrains for heavy-duty trucks.
Read More →
Trucking Executive Warns Fuel Spike from Middle East Conflict Hitting Fleets Fast
Mike Kucharski, vice president of refrigerated carrier JKC Trucking, says diesel price jumps tied to global instability are squeezing carriers already struggling with weak freight rates.
Read More →
Smarter Maintenance Strategies to Keep Trucks Rolling
In today’s cost-conscious market, fleets are finding new ways to get more value from every truck on the road. See how smarter maintenance strategies can boost uptime, control costs and drive stronger long-term returns.
Read More →
Researchers Demonstrate Wireless Charging of Electric Heavy-Duty Truck at Highway Speeds
Purdue researchers demonstrated a high-power wireless charging system capable of delivering energy to electric heavy-duty trucks at highway speeds, advancing the concept of electrified roadways for freight transportation.
Read More →
EPA Wants to Know: Are DEF De-Rates Really Needed for Diesel Emissions Compliance?
The Environmental Protection Agency is asking diesel engine makers to provide information about diesel exhaust fluid system failures as it considers changes to emissions regulations.
Read More →6 Dashcam Tactics to Improve Safety & ROI
6 intelligent dashcam tactics to improve safety and boost ROI
Read More →
California: Clean Truck Check Rules Still in Force for Out-of-State Trucks, Despite EPA Disapproval
The Environmental Protection Agency said California can’t enforce its Heavy-Duty Inspection and Maintenance Regulation, known as Clean Truck Check, on vehicles registered outside the state. But California said it will keep enforcing the rule.
Read More →
Justice Department Pulls Back on Criminal Prosecution of Diesel Emissions Deletes
The Trump administration has announced it will no longer criminally prosecute “diesel delete” cases of truck owners altering emissions systems in violation of EPA regulations. What does that mean for heavy-duty fleets?
Read More →
