More than 37 percent of all diesel medium- and heavy-duty commercial trucks registered in the U.S. are now equipped with newer technology clean diesel engines (2007-MY or newer with near-zero particulate emissions), according to new data compiled by IHS Automotive for the Diesel Technology Forum.

In addition, nearly 22 percent of all diesel trucks in operation are equipped with the newest clean diesel technology (2010-MY or newer) that also produce near-zero nitrogen oxide (NOx) emissions.

More than 95 percent of all heavy-duty trucks are diesel-powered, as are a majority of medium-duty trucks, according to the Diesel Technology Forum.

"New diesel vehicles are increasing their penetration in the marketplace because they are more fuel efficient, in part, due to meeting the requirements of Phase 1 of the U.S. EPA/NHTSA Fuel Efficiency standards that went into effect in 2014. We fully expect that diesel technology will remain a dominant factor in achieving the president's newly proposed second round of truck efficiency and emissions standards," said Allen Schaeffer, the forum's executive director.

Class 3-8 trucks on the road from 2007 to 2014 saved 880 million gallons of diesel fuel, and nine million tons of carbon-dioxide, and the new technology diesel engines reduced 1.45 million tons of NOx and 39,500 tons of particulate matter, Schaeffer added.

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).

The analysis of new technology penetration is based on 2014 data of Class 3-8 vehicles in operation in all 50 states and the District of Columbia through Dec. 31.