Roush CleanTech said its propane autogas engine for Classes 4-7 trucks and Blue Bird type C buses has been certified to meet the optional low nitrogen oxide (NOx) level of .05 grams per brake horsepower per hour (g/bhp-hr). 

The engine was certified by both the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB), which is well below EPA's standard of 0.20 g/bhp-hr, and compliant with CARB's optional level of .05 g/bhp-hr.

“Roush CleanTech’s low NOx engine is a great step forward for the propane industry,” said Tucker Perkins, president of the Propane Education & Research Council. 

Roush CleanTech said it has begun installing the new low NOx engines in Ford commercial vehicles and Blue Bird Vision propane school buses with model year 2017 engines.

“Developing the lowest NOx propane engine sends a message that this fuel is comparable to other alternative fuels from a standpoint of emissions,” said Todd Mouw, vice president of sales and marketing for Roush CleanTech, which is based in Livonia, MI.

Roush said propane autogas costs about 40 percent less than gasoline and 50 percent than diesel.