Volvo Trucks North America is now offering its XE fuel-economy integrated powertrain with a 455 hp. rating.

Introduced just last September with a 425 hp. rating, the Class 8 highway package combines Volvo’s D13 heavy-duty diesel with its proprietary I-Shift automated overdrive transmission, rear axle ratings of 2.64 to 2.69, and proprietary powertain control software to deliver a 3% improvement in fuel mileage, according to Ron Huibers, president of North American sales and marketing.

Both XE ratings provide peak torque of 1,750 lbs.-ft. and are designed to keep the D13 diesel within its most fuel efficient operating sweet spot up to 70% of the time, according to Ed Saxman, Volvo Trucks product manager for powertrain. Intended for on-highway long-haul applications, the new higher horsepower option is aimed at those fleets that need higher performance without sacrificing fuel economy, he said.

Overall, the integrated powertrain concept is growing in popularity with Volvo customers, according to Huibers, who said in 2011 80% of its trucks were sold with Volvo diesels and 40% with its automated mechanical I-Shift transmission.