Next-Generation GM Hybrid Powertrain Will Be Four-Mode

FourNext-Generation GM Hybrid Powertrain Will Be Four-Mode

If each new generation of computer processor is able to double the speed of the previous one, is it any surprise that GM's next-generation gas-electric hybrid powertrain for its big pickups and SUVs will be four-mode instead of the current two-mode?

We first heard a four-mode hybrid powertrain was in the works in 2007, during a conversation with then-vice-chairman and product czar Bob Lutz. Now, we've got a bit more information after our latest visit to GM earlier this week for a product and technology preview.

"It's all about any hybrid system," said John Turzewski, GM's lead development engineer for full-size truck hybrids. "As you evolve and go through your next generation, it's cost reduction, smaller, lighter and better packaging. There's lots of improvement all along those lines."

The two-mode hybrid powertrain uses an electrically variable transmission that houses two 60kW electric motors that can power a truck on their own up to about 25 mph, depending on driving conditions. It provides an almost infinite range of gears, but it also has four fixed gears, like a conventional automatic transmission, that can be manually selected with the column shifter. The electric motors seamlessly support a 6.0-liter V-8, individually or in tandem, at low and high speeds, helping the engine enter fuel-saving four-cylinder mode sooner and stay in it longer to achieve maximum miles per gallon.

Will the four-mode hybrid have twice as many electric motors as the two-mode? Turzewski isn't saying, but we're willing to bet there will be more than four fixed gears to help run the truck more efficiently in a wider array of driving conditions.

GM has already promised that its next-gen hybrids will be able to tow 50% more than today's 6,100-pound maximum. Today's trucks also rate the best fuel economy in the segment at 21/22 mpg city/highway with two-wheel drive.

The four-mode hybrid system is expected to arrive by 2013.


A hybrid 6 cyl diesel would be nice...

Some type of turbo direction injection 6 (think ecoboost) hybrid combo would also be nice.

I would REALLY like to see a homogeneous charge compression ignition engine.

I think a series plug-in hybrid is the only way to do it (like the Volt and the Fisker Karma). Diesels might not be the best for this application as RPM should be more constant, and diesels tend to "glaze" at constant rpm.

Diesels don't have to glaze at constant RPM. They glaze under continuous low load. That's why diesel generators, diesel cargo ships, and diesel-electric trains all run with a relatively high load all the time (and at constant rpm). I don't really know if a hybrid truck will ever make sense. It seems they come at an exteme price, both in the monitary sense and in the performance sense. I want a truck to carry and pull things. If it gets decent mileage, that's great. If I have to make two trips because I have a hybrid truck, how much fuel does that really save?

The author of the article is heading down the wrong road with the speculation around 2 mode referring to the number of motors. 2 mode refers to the number of ranges of the hybrid assistance - low and high speed. So the next version will have 4 assistance ranges Low, Med, Med-High, Highway or something like that.....

BMW's new dual mode hybrid has 7 fixed gears, vs. GM's 4.

I'd have a question as a European guy: Is there in USA a true demand on the hybrid pickup trucks or is it more a government made hype? Even here in "ecologic" EU so kind of cars like the very ugly Toyota Prius aren't hype and best sellers! People attaches more importance to further service of those technologically complicated engine concepts... Honestly said - You're deserving for more simply diesel engines, that get good MPG & lot of torque - they the right engines for You!

There isn't true demand for hybrids period, let alone, hybrid pickup trucks. The Prius loses money. They are only making them to keep Obama off their backs. See more at the link.

VOLT is not a series plug-in hybrid. It is "power split" which combines best of both series plug-in hybrid and parallel plug-in hybrid.

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