• Aug 14, 2009
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, this new transmission 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 yet another five percent.
The new version will have updated electronic control strategies based on the work done for the new 2011 Chevy Equinox with the four-cylinder engine. The Equinox manages a 32 mpg highway rating. These new controls developed for the Equinox will contribute three percent of the improvement for 2012 models like the Cruze compact.

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 that should yield another incremental improvement in efficiency, but no announcement was forthcoming about timing.

[Source: General Motors]


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  • 43 Comments
      • 5 Years Ago
      I'm just hoping that with the extra gear or two these new trannies have that they will have designed the gearing for real world use and not just to inflate the EPA numbers.

      Most highways are 65mph (and alot of times tend to go a bit faster) so they really should have that top gear set to kick in around 55-60, then you could cruise at 2000rpm rather than the 3000-3500 most cars seem to.
        • 5 Years Ago
        Have you not driven a modern 6spd car recently? My mom's '09 Malibu has the 3.6L and the 6spd auto and it turns well under 2k RPM at 65mph.

        Thing is, that is purely to inflate EPA figures rather than real world driving. The engine tends to have to shift fairly quickly whenever the grade changes or minor speed changes are needed. If they really wanted to gear it better for real world driving, they'd have made the gearing shorter and allowed it to turn a bit faster at highway speeds to keep it from having to downshift so often. But, then it wouldn't achieve quite the MPG's that it does with the higher gearing. It's a tradeoff and GM opted for higher MPG's over better performance. Such is the state of the auto industry today.

        The other reason that most engines turn faster at highway speeds is that they don't have the low-end power to maintain speed at those low RPM's that you wish to have(particularly 4cyl cars). There is a reason that the Vette and Viper can turn over 1200RPM at 60mph but less powerful cars have to rev much higher. A Vette can make the same HP at 1200RPM as a Sentra makes at 3500RPM.

        Mandating an RPM is one thing, but making sure the engine has the power to utilize the garing at that RPM is a completely different matter.
        • 5 Years Ago
        I also happen to have a 2010 Hyundai Sonata as a rental car currently and I noticed tha tit also turns under 2000 RPM at 60mph as well. I think it's a 4cyl too, but I haven't popped the hood. Just feels and sounds that way.
      • 5 Years Ago
      It's funny that all of the sudden GM is starting to actually develop and engineer things that take a step forward. They probably could have used that for the last 25 years or so.

      I still think it's too late and they're just doomed to play catch up with Honda, Ford, Hyundai, etc.
        • 5 Years Ago
        Interesting, you're the first guy on here to try to say Delphi isn't part of GM. Most people want to bundle them together since Delphi is in financial trouble too.

        The work on the suspension was done for years before Delphi split from GM.

        Bosch developed their own form of stability control, it doesn't mean GM didn't develop it too.

        I was unaware of the NSX electric steering. But I don't really view deployment of it on a car that shipped such limited numbers as being as big a deal as GM putting it on the Vette in 1997 and the Malibu a year later.

        I guess Ferrari never did crap either, because Magneti Marelli makes their transmissions and other technological devices.
        • 5 Years Ago
        Electric Power Steering was first on the Honda NSX, not a GM Car.

        ESP was developed by Bosch, not GM.

        MagneRide was developed by Delphi and first used in 2002 by GM....1999 was the first year for Delphi to be a publicly held corporation. So no GM did not develop MagneRide, Delphi did.

        Nice try.
        • 5 Years Ago
        If only they had developed magnetorheological suspensions, electric power steering or stability control. Oh wait, they did.
      • 5 Years Ago
      Wow people really are stupid to trust that GM could build a transmission that wont fall apart. Maybe they will do as good of a job on it as they did on the trany problems the camaro has.Oh yah some retard will say GM didnt build the trany for the Camaro, but they still approved it! hahaha.....to all you GM losers....Get a GRIP! LOSERS!!
        • 5 Years Ago
        I guess BMW must be stupid to buy GM transmissions for their cars like they have been for years, or the people who buy BMW's with GM transmissions. Or Ferrari for licensing their magnetic shock technology. You obviously are clueless
        • 5 Years Ago
        "Oh yah I have worked for GM..."

        And you hate them because they fired you/laid you off. We understand your hurt. But this forum is not the place to express it. We want to talk about products and technology. I'm sure if you look hard enough you can find a blog/forum for ex-GM employees.
        • 5 Years Ago
        You worked for GM? Oh yeah?!? I worked on the moon for a secret NASA project!
        • 5 Years Ago
        What's the Japanese word for troll? トロール

        Right-o. This one's hungry.

        I seriously don't understand how Autoblog doesn't have/enforce an anti-trolling policy. Having posters like ih8gm, ToyotaGuy, laser, Brian, et al., really degrades the quality of your blog. It's one thing to be overly supportive of Company X. It's another thing to just rabble on, instigating fights, and what not.
        • 5 Years Ago
        Oh yah I have worked for GM and I do know what they are all about and it isnt building a quality car
        • 5 Years Ago
        Even GM employs janitors...
      • 5 Years Ago
      I see GM is still trying HARD to beat toyota, but they always end up having an epic fail.

      "The Equinox manages a 32 mpg highway rating" WOW.
        • 5 Years Ago
        @ToyotaGuy

        Your name makes you lose all credibility when it comes to an unbiased argument. As good as Toyota's are, the guts of the RAV4 drive train has been around 2001 and isn't exactly what I would call class leading. 32MPG isn't any kind of fail at all.
        • 5 Years Ago
        So you think your RAV4's 27 highway rating is better? I see no "epic fail" in getting a comfortable, affordable CUV to have the mileage of a compact car.
        • 5 Years Ago
        I also root for the Japanese baseball team when they come over here. NOT.
        • 5 Years Ago
        How nice, a fanboy who joins us today. If I wanted a appliance id drive a Toyota, but seeing as most of us are enthusiasts here and prefer something engaging GM has a better offering.
        • 5 Years Ago
        i wouldn't call the equinox engaging either, fanboy.
        • 5 Years Ago
        Equinox or RAV4, they are both fundamentally flawed automobiles. Their height destroys their aerodynamics and handling. Why can't Americans buy normal hatchbacks or estates that aren't disguised as SUVs?
        • 5 Years Ago
        "the guts of the RAV4 drive train has been around 2001 and isn't exactly what I would call class leading."

        The RAV4 I4 was new for MY2009 and is thoroughly modern in all regards. The transmission is a dinosaur.
        • 5 Years Ago
        I'm so sick of the phrases "fail" and "epic fail". Will you 21-year olds please put down your iPhone and text-chat phones, read a real book, and add a few more words to your English vocabulary.
      • 5 Years Ago
      It's so refreshing to see good news coming out of the GM Camp. I believe that many want more reasons to buy US and news of fuel efficiency, electric cars, Hot looking Camero's are just the beginning. Go GM!
      May the US lead again..
        • 5 Years Ago
        How much you want to bet the capabilities of this transmission will be diminished after GM's beancounters finish cost-cutting the hell out of it?
        • 5 Years Ago
        Maybe Nissan should inquire about those twin clutch transmissions ;)
        • 5 Years Ago
        If that dual range CVT design is scaled up to the high torque versions of the CVT, then Nissan can get a few more years from CVTs.
        If the ratio spread increases from 5.4:1 to 6.6:1, that would be great.
        • 5 Years Ago
        @ Ike...
        GM powertrains are some of the best in the business. I guess you would have preferred to own one of the 1.2 million honda five speed transmissions that were not designed properly for Accords and affiliated models causing a high failure rate. Maybe one of the 600,000 Honda transmissions that were later recalled in Oddyssey, Pilot and MDX vehicles. Perhaps one of those grinding Honda six speed manual trannies? Oh yeah what trim of 2009 Accord is avaliable with a six speed auto?... That's what I thought!
        • 5 Years Ago
        I seem to recall Bob Lutz telling us that it was going to cost an additional $5,000 per vehicle to make them more fuel efficient and environmental friendly.

        Guess those scare tactics weren't true. (Edit: Kind of like the scare tactics of the Right on healthcare, but that is another rant).

        What is good to see is that these MPG improvements will come in 5% increments like this. When you add all the improvements together you can see how easy it would be to make our vehicles more fuel efficient.
      • 5 Years Ago
      I love hearing positive news from any of the Big 3. I am all for innovation so I say go ahead. I just wish I could hear some positive news from Chrysler for a change.
        • 5 Years Ago
        You must have missed the introduction of the all new Jeep Grand Cherokee at the New Your auto show. It was well received and will be in production soon. Did you know that the 200C concept was green lighted for production? That concept was very well received - here and in Europe.
      • 5 Years Ago
      "Next-gen GM six-speed automatic to boost mileage another 5 percent . . . "

      Bring it!!!
      • 5 Years Ago

      now if we can get ford to get some 6 speed gear boxes especially in the mustang!

      • 5 Years Ago
      Go GM Go!! Finally, GM is making the products that they were capable of doing all along. I will now get rid of my Toyota for an American car. I've waited long for this day.
      • 5 Years Ago
      Why not develop a 7-speed automatic transmission like Mercedes-Benz or an 8-speed automatic transmission like Lexus, BMW, and soon-to-be Hyundai?

      If GM equipped all its Chevrolet and Buick models with 7-speed automatics, it would yield a bigger advantage over Honda and its ubiquitous 5-speed automatics and even Toyota with its 6-speed automatics.

      As for Cadillac, it needs, at minimum, an 8-speed automatic to keep pace with Lexus, BMW, and Hyundai.
        • 5 Years Ago
        GM had better gets its longitudinal 8 speed auto out immediately. 1-7 for tow/haul, 2-8 otherwise.
        The 3.0 V6 is turning out to be a dud, even with a 6 speed auto. Looks like an 8 speed is necessary.
        http://www.zf.com/corporate/en/products/innovations/8hp_automatic_transmissions/8hp_automatic_transmission.html
        I like how in the interview section, the Dr. say they are 11% away from an ideal transmission, so when will the 9 speed auto come out? (8/9th from 'perfection'?)

        Hyundai's 6 speed auto looks pretty good
        http://www.hyundainews.com/Media_Kits/2010_Models/Santa_Fe/Specifications.asp
        Where is the Azera 3.3 V6 with 6 speed auto?
        • 5 Years Ago
        Actually, I believe that ZF claims improved weight/lower complexity in addition to improved gear ratio selection for their 8-speed RWD family vs their 6RWD. True, there is a point of diminishing returns, but if anyone thinks that these companies are throwing money down the drain or out the window to put another gear ratio in play, these aren't the times for that. There is a technical advantage to 7/8 speeds in ~certain~ applications.

        @montoym... not sure why you note it as a ~bad~ thing that the transmission has to shift to react to small/quick changes in throttle... that's the whole GD point!!! The faster the AT can react, the more likely it is to meet the driver's demand.

        This new GM transmission upgrade will have the guys at Toyota scratching their heads and wondering why they spent more $$ to get the same effect. GM is on to something.
        • 5 Years Ago
        Right gearing is more important than more gearing.
        • 5 Years Ago
        ZF is taking credit for the fuel savings from start stop. Sorry if I'm not knocked over by their arguments. Perhaps the rottenness of the ZF 5-speed in my Audi is a contributing factor.
        • 5 Years Ago
        Please explain why they NEED a 7-speed or 8-speed? I am old enough to remember when a vibrator was a car part and not something banned in Alabama, but consider my automotive tastes relatively modern. Still, I cannot get past people's fascination with the "whirly-bits" factor. If there is no actual gain by adding more speeds (and the resultant bulk and weight), why bother?

        I'm not knocking your comment; I just want to know why you believe adding more and more gears to the gearbox is some sort of necessity beyond bragging rights at wine-and-brie parties.
      • 5 Years Ago
      doesn't gm hold the most automotive patents?
      • 5 Years Ago
      Sounds good. 6-speed AT will be the mainline transmission for the next 4 years, they do need to compete effectively on creating them.

      GM does need a dual-clutch too, for the Vette. I don't know if waiting for the 2012 C7 makes sense though.

      Many (if not all of) the 6Ts are shared with Ford (as 6Fs), does Ford have similar improvements? Maybe they already have them?
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