Clean diesel truck engines and emissions control systems now make up on average 30% of all heavy-duty commercial vehicles in operation in the U.S. as a result of adoption by fleets over the past five years, according to a recent report commissioned by the Diesel Technology Forum.

Nearly 3 million heavy-duty diesel commercial vehicles introduced from 2011-2016 in the U.S. are being powered by the latest clean diesel engines. Diesel Technology Forum executive director Allen Schaeffer said that in that 5 year period, clean diesel engines have saved 4.2 billion gallons of diesel fuel and reduced 43 million tons of carbon dioxide, 21 million tons of NOx and 1.2 million tons of particulate matter.

"Because diesel overwhelmingly dominates the heavy-duty truck sector and is also the number-one power source for medium-duty vehicles, the transition to newer generations of clean diesel technology (2011 and later model years) is significant,” said Schaeffer. “The 30% national average is up from just 25.7% last year.”

The research also found that benefits would increase with more adoption of newer clean diesel trucks. By percentage, Indiana is the state with the highest adoption rate of clean diesel Class 3-8 trucks at 51%, while green technology stalwart California ranks 46th at 25%.

“If California were to achieve the same new technology penetration as Indiana, it can eliminate another 200,000 tons of NOx and 11,000 tons of fine particles that would bring cleaner air faster to all California communities than any other strategies," said Schaeffer.

The research was conducted by HIS Markit, a global technical marketing research firm. State rankings data is based on Diesel Technology Forum analysis of IHS vehicles in operation in operation data representing Class 3-8 diesel trucks from model year 2011 through 2016 in all 50 states and the District of Columbia through Dec. 31, 2016.

"The U.S. trucking fleet is transitioning to newer clean diesel technology which means immediate fuel savings, lower greenhouse gas emissions and cleaner air,” said Schaeffer. “This newest generation of clean diesel trucks have NOx emissions that are 99% lower than previous generations along with 98% fewer emissions of particulate matter, resulting in significant clean air benefits throughout the U.S.”

The Diesel Technology Forum is a nonprofit that seeks to raise awareness about the importance of diesel engines, fuel, and technology.