The GM/DCX/BMW Two-Mode Hybrid collaboration
Click the image for a high res gallery of the GMT900 hybrids
When General Motors gave us our brief (and I mean brief, it was only about ten minutes behind the wheel) first exposure to the new Tahoe and Yukon hybrids the other day they weren't there alone. Along with the GM chief engineers and vehicle line executives, were representatives from DaimlerChrysler and BMW. The Two-Mode hybrid system was originally created by GM's Allison transmission division for buses and other heavy duty vehicles but GM decided to partner with DCX and BMW to migrate the technology to light duty vehicles.
While the decision to apply the hybrid system to the big SUVs may seem a highly dubious one from the perspective of green car fans, GM does have some rationale for their choice. The new Tahoe and Yukon are only the first of many vehicles that will be getting this technology in the next few years including significantly smaller vehicles than the ones we drove. Although declining in popularity in an era of higher gas prices, the fact remains that Americans still buy a lot more big trucks every year than they do small cars.
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Gallery: 2008 GM 2-Mode Hybrid SUVs
Given the thirst of those millions of trucks that are sold every year it makes sense to do whatever they can to improve them. Because the Two-Mode hybrid system offers advantages over a wider operating range than other competing systems it can provide benefits to these vehicles in both urban use and the longer road trips that they are often used for. Admittedly an SUV that gets 22-23 mpg isn't green by any stretch of the imagination, but as has been argued here before, "Is any internal combustion engine car ever really green?" While we work on new drivetrain technologies for the future, we have to optimize what we have today and at least try and make it "greener."
The partnership is creating at least three variations of the Two-Mode transmission for different applications. The first one is the large RWD/AWD variant that is being used in the GMT900 trucks and the Dodge Durango/Chrysler Aspen. Next up is a transaxle version that will appear in the Saturn Vue in the second half of 2008 as a higher end upgrade to the mild hybrid belt-alternator-starter system that will remain available. The two-mode Vue will also get a version with the NiMH battery pack replaced by a lithium ion pack and plug-in capability. Undoubtedly it will turn up in other vehicles as well. How about the Outlook, Acadia or maybe the Chrysler minivans?
The third version goes back to the longitudinal arrangement and is intended for passenger car type applications. As expected no one likes to talk about future products but BMW did acknowledge that this third version would be the version that they use although no further details would be revealed. This one is also likely to turn up in Mercedes vehicles and seems like a likely candidate for the next-gen Chrylser LX platform. Unfortunately everyone was non-committal about other engine combinations such a Duramax diesel hybrid which seems like a natural.
One question that was answered was where the transmissions would come from. General Motors will be building them at their Baltimore transmission plant and supply them to DaimlerChrysler and BMW. They will all use basically the same hardware with the main differences being in the cases to fit the individual manufacturers engines and chassis.
Each manufacturer will also do their own calibration work to meet their own performance requirements. The integrated design is configured to allow it to be adapted to most existing vehicles without major redesign. Together the three partners have adapted this technology to fit into almost any vehicle. So we have many more applications of this system to look forward to in the next few years.
Reader Comments (Page 1 of 1)
Derek 8:13AM (5/03/2007)
roughly 20 hours up and not a single comment? Alright, it's no 50mpg Prius so you might not get the same green rush, but start doing the math. Say you can sell 25% of new SUV's (and trucks?) as hybrids. With a 20% reduction in fuel used on each (=25% economy improvement) the potential gas savings are huge. The effect this could have on US fuel consumption completley blows the Prius out of the water. It won't take long at all for the total gallons saved by these vehicles to exceed the gallons saved by all the current hybrids on the road. This could be a very big thing for the environment. Of course, I hope that eventually America will come to its senses and start buying smaller vehicles that are more fun to drive but it's a market economy and people want trucks so let's at least give then clean(er) ones.
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M B 3:15PM (5/04/2007)
That rationality is exactly why GM started their hybrid research with passenger buses. Besides being large and using lots of fuel, city buses spend most of their time operating in a stop and go driving cycle which is where hybrid systems have the biggest advantage over conventional drivetrains. GM chose to focus on the end of the spectrum where improvements in fuel economy would have the largest impact on the environment and the economy. It should also be noted that while the prius and civic hybrids don't do much in the overall picture, 100mpg prius hacks have done a lot for the public image of this technology and for getting everyone to think about better milage for the sake of their pocketbooks if not for the sake of the environment.
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Arroba 10:44AM (5/04/2007)
The problem is that some people who would otherwise trade their suv for a normal car won't do it because a hybrid suv mileage is good enough for them.
But I guess it's still an overall improvement over the current situation.
PS: Why not ditch the frame construction and go with a unibody? They could easily save 300 pounds with that.
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ninjatickets 6:19PM (5/31/2007)
The reason why heavy duty vehicles are body on frame is because the loads they carry actually bend the frames, and body on frame vehicles can "bend" easier than the ultra stiff unitbody. As well in offroad situations a unitbody can actually break. In a few words, body on frame is better suited to handling great forces without any future damage to the structure.
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ninjatickets 6:23PM (5/31/2007)
To #3, it may be to your great displeasure, but you should realize that GM has the most advanced car systmes on the drawing board with their new full electric engines, hybrid electric generating concepts that may hit the market as early as 2010. I am a physics major and their design of a plug in charge with a diesel generator back up, full electric power is much more advanced than other dual propulsion hybrids. The GM method is what is used on the most efficent ships, and as an added bonus the generator can be dropped for a fuel cell when the time comes.
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