ROUSH CleanTech has developed a propane autogas engine that is 90% cleaner than the EPA heavy-duty engine standard. This achievement comes after just last year, the company introduced a propane autogas engine that was 75% cleaner than the EPA standard.

With this latest design, ROUSH's propane autogas engine is the first certified by the California Air Resources Board (CARB) to meet optional low oxides of nitrogen emission standard for heavy-duty engines, according to the company.

The new CARB certification covers the 6.8L V-10 3-volt propane autogas engines for Class 4-7 vehicles. Installation of the optional ultra-low NOx engines has begun with some 2018 Ford commercial vehicles and Blue Bird Vision propane school buses.

Class 4-7 medium-duty trucks and buses equipped with ultra-low NOx engines are expected to be very competitive in seeking funding from the Volkswagen Environmental Mitigation Trust settlement.