At the Mid-America show Mack Trucks introduced its Super Econodyne powertrain package, claimed to provide a 3.5% improvement in fuel economy.

It uses all-Mack proprietary components -- MP8-445SE engine, mDrive automated manual transmission, C125 proprietary drive axles, and custom software -- and is rated up to 88,000 lb GCWR.

The central idea, not unlike Volvo's XE13 system, is what Mack calls the “down speed” feature. Super Econodyne is engineered to drop engine speed more than 200 rpm at a highway speed of 65 mph, cruising at 1160 instead of 1380 rpm. This reduces fuel consumption by up to 2% compared with previous engine models, says Mack, while its proprietary C125 drive axles are claimed to deliver an additional 1.5% fuel economy saving.

The Mack MP8-445SE offers 445 hp and up to 1760 lb ft of torque. The C125 axles have a 2.66:1 ratio. All powertrain components communicate with each other via Mack software.

The company says the system does its trick without compromising power or performance.

The low-speed Econodyne engine comes out of the 1960s, notes Dave McKenna, Mack director of powertrain sales. “Historically, we’ve insisted on gearing fast, running slow. Now, we’ve designed a completely integrated system to run efficiently at 450 rpm above idle speed when before it was 700 to 800 rpm above idle speed.”

The Super Econodyne package is available on Pinnacle models.