Roush CleanTech standardizes ultra-low NOx engine package

May 23, 2023 By    

Roush CleanTech received California Air Resources Board (CARB) certification for 2023 model year propane engines at 0.02 grams per brake horsepower-hour. Previously available as an added-cost option, the ultra-low nitrogen oxide (NOx) emissions package will become standard on every propane engine sold by Roush CleanTech, the company says.

Roush CleanTech truck photo: LP Gas staff

A Roush CleanTech F-550 on display at the 2023 NPGA Propane Expo in Nashville, Tennessee. (Photo: LP Gas staff)

The engines emit 90 percent less NOx emissions than allowed under 2023 regulations and are 60 percent cleaner than California’s 2024 low-NOx standard, without compromising performance or efficiency, according to Roush CleanTech.

“Customers can rest easy knowing that Roush CleanTech propane engines provide ultra-low NOx emissions with no added cost today. And, we are well on our way to meeting California and EPA’s emissions standards for 2027 and beyond,” says Todd Mouw, executive vice president at Roush CleanTech, in a news release.

Fleet operators purchasing 2023 models will have a greater chance of accessing state and federal funds that incentivize near-zero-emissions vehicles, including the Infrastructure Investment and Jobs Act’s Clean School Bus Program and the Volkswagen Environmental Mitigation Trust settlement, among others.

Roush CleanTech first released low NOx engines in 2018. In 2021, it received CARB’s ultra-low 0.02 grams per brake horsepower-hour certification for Blue Bird school buses and commercial vehicles.

Roush CleanTech says its newest technology and a growing renewable propane supply showcase how the fuel is no longer a bridge to help fleets reach U.S. emissions goals, but rather a destination transportation energy.

There are more than 37,000 advanced clean vehicles equipped with Roush CleanTech’s engines on the road today, including 18,500 school buses in 1,000 U.S. school districts.

About the Author:

Brian Richesson is the editor in chief of LP Gas Magazine. Contact him at or 216-706-3748.

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