Silverado Hybrid BadgeEnlarge Photo
The Two-Mode Hybrid project was hailed as a model of technical cooperation when it was announced five years ago. But now the partners are going their separate ways, and the complex hybrid system may end up solely as a General Motors technology.
GM said in late 2004 it would partner with Daimler and Chrysler (then a single company) to develop a shared hybrid system for sport utility vehicles and pickup trucks, derived from a larger system designed for GM transit buses. BMW signed on in September 2005.
The system is made up of an electric continuously variable transmission (eCVT) containing two electric motors, four fixed gears, and various clutches and planetary gearsets; a nickel-metal-hydride battery pack; heavy-duty power electronics; and millions of lines of sophisticated control software to manage all of it.
2010 BMW ActiveHybrid X6, Bal Harbour, FloridaEnlarge Photo
2010 BMW ActiveHybrid X6 engineEnlarge Photo
2010 Mercedes-Benz ML450 HybridEnlarge Photo
2010 mercedes benz ml450 hybrid 007Enlarge Photo
Sole survivor: GM?
Numerous reports this year indicate that partners BMW and Mercedes-Benz are moving away from using the Two-Mode in future models.
Meanwhile, Chrysler's five-year plan notably omitted electric-drive vehicles. Both electric vehicles and hybrids took a back seat to smaller and more efficient gasoline engines (including partner Fiat's MultiAir technology) and even small diesel engines.
Collaboration ends, offices shut
The joint Two-Mode R&D and engineering efforts in Troy, Michigan, known as Global Hybrid Cooperation, ended last June. The lease on those offices expires in December, and GM staff have been moved to facilities at the Warren engineering center and elsewhere.
Similarly, Chrysler engineers have relocated to its technology center in Auburn Hills, and Mercedes-Benz is now using its former hybrid facility in nearby Redford for R&D on an expanded variety of alternative powertrains.
Future lithium-ion battery
GM acknowledged plans for the second generation of the Two-Mode Hybrid system, complete with lithium-ion battery pack, in very broad terms at a technical event held last month at its Warren, Michigan, battery lab.
The company has extensive experience designing and validating the lithium-ion battery pack for its 2011 Chevrolet Volt extended-range electric car, as well as plans for a more powerful second-generation mild-hybrid system to be introduced next year.
Smaller, lighter, cheaper?
That means that GM is likely to fit the second generation of its Two-Mode systems with smaller, lighter, equally powerful lithium-ion battery packs. Those packs should benefit from every effort GM makes to cut the cost of Volt packs--which hold 10 times the energy of a Two-Mode pack--to make the hybrid option more affordable and give it a better payback period.
That's just one of several steps the company will have to take to continue selling half a million full-size pickup trucks in the face of rising fuel-economy standards between now and 2015.