LISLE, Ill. — Navistar announced today it is now shipping its first International DuraStar and WorkStar vocational trucks with its 9- and 10-litre SCR engines.

The company says the engines provide up to an 8% fuel economy improvement over previous generations.

“Our field test customers are seeing positive results – with our new trucks registering significant fuel economy improvements,” said Bill Kozek, president, North America Truck and Parts, Navistar. “Our vocational trucks with 9- and 10-litre engines are also experiencing fewer active regenerations while still delivering the durability and power that customers expect from International trucks.”

Navistar says it has conducted field-testing with customers across a wide range of duty cycles in various parts of the country, including hot and cold climates.

“We’ve run our DuraStar with the 9-litre for around 40,000 miles during the last two months,” said Robbie Easley, owner, Easley Trucking. “We haul mail and the 9-litre has performed well on the steep hills our trucks climb daily. This truck runs between Phoenix and Yuma, Arizona, one of the hottest environments you can find, and it hasn’t missed a beat.”

The International DuraStar can be had with a 9-litre engine producing 275-330 hp and 860-950 lb.-ft. of torque. The WorkStar can be ordered with 9- and 10-litre Navistar engines producing 275-350 hp and 860-1,160 lb.-ft.