Next-gen GM 6-speed automatic to boost mileage another 5 percent
It's only been a year since General Motors launched its 6T40 six-speed automatic transmission for mid-size and compact cars. When it was introduced, it brought with it a five percent bump in fuel efficiency. The engineers at GM Powertrain are now developing a second-generation variant of the 6T40 for introduction in 2011 that will bump fuel efficiency by another five percent. The new version will have updated electronic control strategies based on the work done for the new Equinox four cylinder. The Equinox managed a 32 mpg highway rating. The new controls will contribute three percent of the improvement for 2012 models like the Cruze.
Another two percent improvement will come from refinements to the guts of the transmission. Changes to the hydraulic valve body, friction plates and variable flow solenoid will cut internal pumping losses and friction.
GM is also working on its own in-house developed dual clutch transmissions. GMPT is developing a dry clutch system which should yield another incremental improvement in efficiency but no announcement was forthcoming about timing.
[Source: General Motors]
Reader Comments (Page 1 of 1)
Ray 8:10PM (8/14/2009)
Well worth the millions spent in R&D. GM is truly saving the planet with this one. Look everyone they are really trying hard. Time to buy. Be sure and inflate your tires properly or you will loose the efficiency gains made by this innovation.
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Jon 3:36AM (8/15/2009)
Who said this particular innovation cost millions?
UH2L 3:18AM (8/15/2009)
Just a loser comment that shows how little you know about automotive powertrain engineering and how little credit you give to a company that is getting measurable fuel economy gains at no cost to the consumer.
Brian 10:22PM (8/14/2009)
If it is still in development how do they know it will boost mileage by 5 percent?
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UH2L 3:19AM (8/15/2009)
They use tests and simulation. That's engineering.
Gordio 3:37AM (8/15/2009)
improving automatics from a 5 to 6 speed is pointless. the torque converter is far less efficient than a gearbox. if they wanna make any meaningful improvements, it would be to ditch torque converters. a stick shift civic si can probably get the same mileage as an automatic regular civic.
Gordio 3:39AM (8/15/2009)
I forgot to mention, since americans don't like driving manual, GM (and others) need to start considering manumatics. Only afterwards should they consider increasing the gear ratios.
downtoearth 10:24AM (8/15/2009)
Gordio:
> the torque converter is far less efficient than a gearbox.
Torque converter remains locked by an auxiliary clutch some 99% of the time and introduces no losses.
jpm100 2:14PM (8/16/2009)
I know manuals give better mileage by professional drivers trained to execute the various government cycles. This probably includes people who track their mileage and are alway consciously try to maximize their mileage.
But there's a lot of people who don't shirf like a professional and some downright suck at it. I'd like to know what their comparative mileage is.
SumideXE 11:02PM (8/14/2009)
I don't think your GM bashing is justified.
GM was one of the first major automakers to introduce direct injection to their motors. This is a major step. They *are* trying.
That being said, they've been behind in fuel economy and efficiency ( aside from a few models here and there ) for a long time. I think the new CAFE requirements are spurring a lot of this on.. but hey.. you gotta give them credit.
5 percent here.. 10 percent there.. it adds up.
Look at the new chevy equinox.. 2.4 DI 4 banger that produces enough torque to move a ~3700lb SUV and somehow gets 32mpg on the highway.
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Tim 4:25AM (8/15/2009)
Booste milage 6%? How much does it add to the cost of the vehicle? What's the Return on Investment?
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Detfan 9:08AM (8/15/2009)
Let's see. The Cobalt gets better mileage than the Corolla, Civic, and Sentra. The Malibu gets better mileage than the Camry, Accord, and Altima. The Impala gets better mileage than the Avalon, and Maxima. The HHR and Equinox, and Terrain gets better mileage that the Rav-4, the CRV, the Ford Escape. The GM 8 seat crossovers have a 50% market share and get an industry leading 24 MPG HWY, GM's full size trucks and full size SUV's are industry leading in mileage. Even the Camaro smokes the competition at 29 MPG HWY. GM is leading in most segments in mileage and most people don't even know it.
With the new 6 speed transmission moving the 2012 Malibu to 35 or 36 MPG Hwy, and the addition of HCCI adding another 10-15%, bringing the 2012 Malibu to close to 40 MPG, and other vehicles with similar gains, it is the japanese chasing GM, and they will be for quite some time.
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Ray 11:47PM (8/15/2009)
Not worth it. Why not CVT with little or no gears. On a car that already get 35 miles per gal not worth it. I am afraid this is just a salesman gimmick. Wake me when you produce a EV that has no use for a wasteful trans. I am afraid I will be asleep for 10 years like Cinderella waiting for GM to do the right thing , instead they prefer to fool the public into thinking they are trying.
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RAN 1:51PM (8/16/2009)
Isn't it amazing that GM can manage to come up with direct injection engines and 6 speed transmissions ready for sale at a moment's notice, but even after years to prepare they can't manage to put a simple electric motor and a few batteries together to get any EV models on the market?
Maybe they should hire Jack Rickard, lol.
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Jubei 1:35AM (8/17/2009)
GM is the biggest loser and biggest BS automative manufacturer on the planet. Why would anyone believe anything they say after years of fooling customers with their subpar cars.
Mr Clickerson 2:15AM (8/17/2009)
I don't know about their cars personally, though from what I hear they're of good quality, but I do know first hand about their trucks and SUVs, and there's no bullshit when it comes down to Chevy or GMC trucks. Then again, Jubei the Prius driver, wouldn't know about trucks or any REAL work, because he sits at home all day posting his ass off about how awesome Apple is, how Godly Steve Jobs is, how much Microsoft sucks, and how GM produces subpar cars, even though he has no first hand experience with the last two subjects.
Get a life, you fat, lazy, tard.
senginc 2:19PM (9/14/2009)
most all anti GM or anti American is just pseudo snobery and ignorance of the real facts about American vehicle real use longevity
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