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AutoBlog: Next-gen GM six-speed automatic to boost mileage another 5 percent

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Filed under: GM

next-gen-6t40.jpgIt'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]

Next-gen GM six-speed automatic to boost mileage another 5 percent originally appeared on Autoblog on Fri, 14 Aug 2009 16:59:00 EST. Please see our terms for use of feeds.

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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.

If true, this is the most interesting bit.

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I think that is what GM registered the "8" for - the DCT would be great for all cars.

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the thing about 5%.... on the cruze that would make it a 42mpg car... based on 40...

everything helps yes. but will it be something that pulls more buyers in...the higher number, usually by 1?

this is applause worthy, but still not ground breaking. Can GM do this across the board with other 6speeds? make the camaro a 30 highway

would that make the vette...27?

seriously applause worthy... keep it up GM.

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Nice, but one huge thing they still need big help on across the board is how to tune & program the 6-speeds in everything. Lots of complaints still, performance issues that can translate to mpg issues because things just are too sloppy, and reflashes galore. The mechanics are there and getting better, the programming of both the engine and more so the trans in so many new GM vehicles needs work.

It's nice that not only are 6-speeds in almost everything, but now about to start having a 2nd gen update, so hopefully they only continue to get better. Oh, if only our '08 Malibu 2.4L had the 6-spd...it would be SO much better performance and mileage wise...

Edited by caddycruiser
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GM needs "best in class" mpg numbers to regain sales, I expect more and more news like this.

Each small gain from a single advance, joined with other small gains, add up to impressive numbers. Weight reduction across the board, driveline and engine improvements, changes in aerodynamics, fuel type and delivery technologies all will figure in. Then there is tire tech, materials tech, accessory simplification, and so on.

Lots of places to find gains in efficiency.

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I understand the need for efficiency improvements, and like Camino said, there are lots of places to find them, but I'd really like to see them make some gains in the fun to drive department with these 6-speeds. Granted not every models purpose is to be fun/sporty, but I would like to enjoy driving regardless of the vehicle.

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