Mercedes Details Powertrain Strategy

Daimler AG's Mercedes-Benz unit plans an array of smaller boosted piston engines, hybrid powertrains, battery systems and fuel cells to meet fuel economy and emission standards over the next 10 years, Autocar reports.

Mercedes notes that turbocharging engines to produce more power at lower RPMs improves fuel efficiency by reducing internal friction. Reducing the number of cylinders does the same.

The company says a slower-turning 4-cylinder engine has about the same internal friction as a higher-revving 3-cylinder engine. But the larger engine is smoother and thus preferred by Mercedes.

Daimler research chief Thomas Weber predicts a future where all vehicles are fully or partly electrified. He envisions a range of powertrains starting with mild hybrids with starter-generators, moving to plug-in hybrids and including all-electrics powered by batteries or fuel cells.

Weber expects the cost of vehicle batteries to drop 50% as their energy density doubles by 2020, Autocar says. He estimates that the improvement would give a B-Class electric a range of as much as 250 miles per charge.

Weber also believe lithium-sulfur chemistries will replace today's lithium-ion batteries, with dramatically higher-performance lithium-air units to follow.