REPORT: GM working on four mode hybrid system
by Sam Abuelsamid on Aug 17th 2009 at 7:55AM 
2009 GMC Sierra and Chevrolet Silverado Hybrids - Click above for high-res image gallery
Our friend Mike Levine over at PickupTrucks.com spent some time talking to General Motors' John Turzewski about the future of the company's hybrid trucks last week and came away with some interesting information.
As we know, the key to GM's two-mode hybrid system is a pair of planetary gear sets that allow blending of engine and electric drive over two different speed speed ranges. This is part of what allows the system to get better fuel economy at highway speeds. The other main difference from competitor's systems is the presence of clutches that allow the gear sets to be locked to four fixed ratios and bypass the electric motors completely for better towing capability.
Levine is now reporting that the next-generation hybrid system could double these offerings to four different drive modes. It's not entirely clear what that means at this point, as GM isn't saying. However, the upcoming two mode hybrids from Mercedes and BMW are upping the number of fixed ratios to seven and GM could build on this idea. The automaker has previously said that the next-gen hybrid trucks would up the towing capacity from the current 6,000 pounds to at least 9,000, so more fixed ratios are likely to be part of the mix.
The next-gen hybrid should arrive around 2013.
[Source: PickupTrucks.com]
Reader Comments (Page 1 of 1)
216 9:06AM (8/17/2009)
why stop at four?
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paulwesterberg 10:26AM (8/17/2009)
They should definitely go straight to 5 mode!
http://www.theonion.com/content/node/33930
Matt 9:42AM (8/17/2009)
If they could cut down on the fluffy body panels that would be nice, too. Give me a truck made for aerodynamics and I'm sold. Or, at least give the Colorado access to a high efficiency drive train. What's keeping the small trucks from getting [comparitively] awesome fuel economy?
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why not the LS2LS7? 1:52PM (8/17/2009)
RWD. Big motors. Huge frontal area and bad aerodynamics. Cheap transmissions (to keep costs down) and low gearings for hauling. Huge, faux, off-road tires. Also, unless you get the two-person cab (very unpopular nowadays), the weight isn't good either. You're basically taking a regular car and adding a box and frame rails to it.
Matt 5:08PM (8/17/2009)
I guess my question is, why have all the efforts been focused on the full sized trucks, and not the smaller ones. It seems like the smaller trucks have not made as big of improvements in fuel economy over the last few years. They are trucks, and some of them are more capable than their larger cousins off road. Small trucks seem like they could be in the 30+ mpg range, and would probably sell a lot better if they were.
NeilBlanchard 10:25AM (8/17/2009)
Hi,
So, is this more efficient? Does this take a 12-14mpg truck and make it 16-18mpg, or is it (much) better than that?
Sincerely, Neil
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why not the LS2LS7? 1:47PM (8/17/2009)
The current two modes get 21/22 already.
http://www.fueleconomy.gov/feg/compx2008f.jsp?year=2009&make=Chevrolet&model=Silverado%2015%20Hybrid%202WD&hiddenField=Findacar
So presumably this would do even better.
Switching from a Silverado (5.3L V8/6-speed) to a hybrid Silverado saves $540 in gas a year/4.9 barrels of oil a year and reduces CO2 output by 2.7 tons per year.
Why criticize this when going from a Camry (V6/6-speed) to a Camry hybrid saves $515 in gas a year/4.8 barrels of oil a year and reduces CO2 output by 2.6 tons a year?
Chris M 5:54PM (8/18/2009)
Yes, but wouldn't switching from a Silverado (5.3L V8/6-speed) to a Prius save a heck of a lot more money and oil and CO2 emissions?
I don't have any quarrels with making hybrid pickups for those who need the carrying capacity, but I do complain about selling pickups as "macho symbols" to those who don't need them.
MikeW 12:41PM (8/17/2009)
I'd like to know how BMW's 7 fixed ratios compare to GM's 3.69, 1.7, 1, 0.73
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why not the LS2LS7? 1:49PM (8/17/2009)
Presumably these become plug-ins. That's 3 modes. Maybe all-EV or V2G is the other mode?
I thought GM's original hybrid trucks with a built-in job site generator (a version of V2G) was a great idea, just not worth paying for. If it can come "free" with future two modes I think it'd be a hit.
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Nick 12:46AM (8/18/2009)
The truck should be lowered a bit, be lighter, have smaller / lighter wheels and better aerodynamics. That alone would save 2mpg.
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Lorena Palin 11:34AM (8/23/2009)
Why not the LS2LS7: RWD does not add inefficiency. The other stuff, yes, but sorry, had to nitpick that one. Sorry, but people knocking RWD is one of my pet peeves.
Chris M: The prius can't haul a boat, or dirt, or lumber. You can haul groceries in one. It's a different market. The hybrid system on a full sized truck saves alot more gas overall than the hybrid system on a small car. Yes, the percentage is about the same (14 mpg to 21 mpg and 34-37 mpg to 45-50 mpg) but that gain on the larger truck will save more gas, because the amount of gas used in the first place is greater.
Now, this system seams VERY powerful, in fact more than most truck owners need. But it would be good for powering 2-ton delivery trucks and the like. I think a scaled down version, for small trucks, would be ideal.
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Chris M 5:41PM (8/23/2009)
Apparently you didn't read all of my post, where I said "I don't have any quarrels with making hybrid pickups for those who need the carrying capacity", That would of course include those who need to haul boats or loads of dirt or big pallet loads of lumber.
I should point out that the 2004 and later model Prius have fold-down rear seats and a hatchback, making them capable of hauling several 8 foot long 2x4 studs, 1x8 fence boards, a few bags of concrete mix, or a few concrete blocks. Not nearly the same load carrying capacity as a pickup, not a good choice for a contractor, but still sufficient for the average homeowner.