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GM Begins Production of New Six-Speed, More Fuel-Efficient, Transmissions

GM has begun production of a new, modular family of Hydra-Matic six-speed automatic transmissions for rear-drive applications. The 6L80 six-speed transmission debuts in the 2006 Chevy Corvette, Cadillac STS-V and XLR-V, and several models of GM’s all-new 2007 full-size SUVs.

Production of the transmissions is the culmination of a $450-million, 3-year investment at the Ypsilanti Transmissions Operations (YTO) facility. By 2010, GM will introduce 10 variants of six-speed transmissions, including front-drive models, which can enhance vehicle fuel economy by up to 4% when compared to four- and five-speed automatics.

The six-speed transmissions feature two overdrive gears and a wide, 6.04:1 gear ratio spread to improve performance and fuel economy when compared with conventional four- and five-speed automatic transmissions. With two overdrive gears, engine rpm is reduced by approximately 9% at 60 mph—a reduction to about 1,500 rpm.

Lower engine rpm can bolster fuel economy because less fuel is used. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle’s cabin.

GM estimates the wide ratio spread can help cut 0-60 mph times by as much as 7% and enhance fuel economy by up to 4%.

Engineering the all-new Hydra-Matic six-speed transmission with a modular architecture enabled engineers and designers to design a transmission that is easily adapted to a wide range of vehicles. Equally important from an operational perspective, the new six-speed automatic’s modular design means any of the four primary variants can be manufactured in the same assembly plant.

As many as 47% of all components are common for all four transmission variants. In theory, different variants could run sequentially down the same assembly line. The new six-speed automatic’s manufacturing plan dovetails completely with GM’s Global Manufacturing System strategy to implement a common manufacturing process and procedure at every worldwide GM assembly plant.

YTO’s six-speed facility is currently configured to produce up to 1,500 transmissions per day. The six-speed RWD transmissions will be featured in 25 different models globally by 2007.

In addition to the Hydra-Matic six-speed RWD family, GM recently introduced the new Allison 1000 six-speed automatic for Duramax diesel-equipped heavy-duty trucks. GM also will introduce a Hydra-Matic six-speed automatic for front-wheel-drive/all-wheel-drive vehicles; it debuts in the 2007 Saturn Aura sedan. GM also will produce six-speed transmissions at additional facilities in Michigan and Europe. GM Powertrain and GM Daewoo are working to develop six-speed transmissions for front-drive global applications.

GM and Ford cooperated on the basic design for the front-drive six-speeds, but they will produce their own versions of the transmissions at separate facilities.



A whole 4% improvement.  More proof that GM still Doesn't Get It.


Hydra-Matic? What is this, greased lightening?

That being said, 4% gain on 20 MPG is 1 MPG. Small, but every bit helps. If GM can squeeze out 1 MPG this way, 1 MPG by cutting weight, and 1 MPG by shifting it's base to a generally more fuel efficient choice, that's 3 MPG. If every GM car got another 3 MPG, we'd be in much better shape.


First it was the 2 speed Powerglide then the 3 speed Turbo hydramatic then the 4 speed overdrive and now a six speed to gain only 4%. So much complexity so many parts and still not as good as Toyota's Synergy Drive which Ford has chosen. More stupid GM management decisions not caused by the UAW.


$450 million for this? Toyota will overtake GM next year in sales. Speaks for itself. It's over. Kiss GM goodbye.

Mikhail Capone

6 speeds are good. Trying to sell 8000+ pounds vehicles to suburbanites who don't need them is bad.

Mikhail Capone

I guess that it is Nissan that is doing the smart thing by pushing for more CVTs.


4% that is funny stuff


stomv, if we are going to cut demand by even 1% per year we're going to need an improvement roughly equal to the age of the typical car at retirement.  That's what, 13 years?  So we'd need 13%, or more.

50% isn't that hard.  We should be aiming for it.

The problem may indeed be the UAW.  There are a lot of workers in transmission plants, making all the fiddly bits for automatics.  If a much simpler electric/hybrid CVT renders many of them surplus, the no-layoff contract requires that they still be paid!  The UAW is unlikely to give up that clause, so bankruptcy is the only way for GM to cut its labor force down to what it needs.

If GM is smart, they've got a ton of designed and tested systems just waiting for the opportunity to build them with a lean manufacturing environment.  I have strong doubts, though.


Engineer if you havnt noticed thats why gm and ford have been investing so much money into future tech 10-15 years from production. They can invest themsevles into "bankruptcy" get out from all the shackles and build new plants where they want making what will sell in 2020 timeframe.


stomv, if we are going to cut demand by even 1% per year we're going to need an improvement roughly equal to the age of the typical car at retirement. That's what, 13 years? So we'd need 13%, or more.

50% isn't that hard. We should be aiming for it.

Right, but that also assumes that the bundle of autos purchased in 2006 will be equivalent to the bundle purchased in 2005. If some folks do "class migrate" to smaller/more efficient models, then we'd get improvemets in fleet MPG without any technological improvements. So, improving the engine by 4%, improving weight by a bit, maybe improving the tires a smidge, it all adds up. Add that to the idea that folks may be shifting classes to more efficient styles, and the fact that the distribution of retired cars isn't uniform throughout the 13 years (more cars 6-10 years will be retired than 1-5 years, for example), and your innitial claim is both (a) not quite accurate and perhaps (b) irrelevant.

Every little bit helps. Incremental improvements are still improvements. Compounding improvements helps yet more.

No company is going to get to 50% improvements in a single step. It takes iterations of improvements. Snarkily lambasting GM for making their products more fuel efficient, if only slightly, seems a bit silly to me.

But then, GM is a dirty acronym around here, and folks love to pile it on.

The problem may indeed be the UAW. There are a lot of workers in transmission plants, making all the fiddly bits for automatics. If a much simpler electric/hybrid CVT renders many of them surplus, the no-layoff contract requires that they still be paid!

Sure, but if the "much simpler elec/hybrid CVT" was indeed cheaper in materials to manufacturer and required less labor, then GM would do it anyway and pay guys to stay home. It'd lower GM's bottom line, and they could send the least productive guys home, thereby improving capital effeciency. So, I don't think it's quite that simple... and it still doesn't make it the UAW's fault -- it's GM's fault for signing a contract it shouldn't have been signing.


4%? One could save more then that by just making sure that his/her tires are inflated properly.

And i dont think smaller engines can suit the 6th overdrive gear well, thats means this is best for fuel hungry big engines.

Are they planning to sell more corvetts and full size SUV?

Although every bit of saving helps, but heck, the source of the problem is not that because of all those big SUVs is unable to save a bloody 4% more of oil here. It is because of SUVs themselves for being so heavy and inefficient! We dont need 3 tonnes of metal to carry less then 2 people.


On another thought, if the engine will run on lower RPM, how about installing one of these transmission into a diesel engine? Since all the high torque comes in from low RPM.


stomv writes:

No company is going to get to 50% improvements in a single step.
I recall an analysis of the Ford Taurus which found an improvement on that order from going to a V6 with a then-standard transmission to a 16-valve 4-cylinder engine with a 5 speed.  It achieved the same performance but the throttling losses at cruise were much smaller, so the economy was a lot better.  No specifics so this may be wrong in some details.

A small turbocharged engine with an asymmetrical compression/expansion ratio might boost the thermal efficiency high enough to raise economy by 50%.  Aerodynamic improvements can make large differences at highway speed, and reduced weight (esp. from smaller engines) reduce energy demands for acceleration.  There are a lot of cars out there which get 50% better mileage than the target RWD platforms, they just have to emulate them.

if the "much simpler elec/hybrid CVT" was indeed cheaper in materials to manufacturer and required less labor, then GM would do it anyway and pay guys to stay home.
Not cheaper in materials.  NdFeB magnets are not cheap, especially not compared to gears that you can just pump through a broaching machine and then harden.  The labor contracts lock Detroit into their allocation of labor vs. materials, even if they can't make the economy improvements they need without increasing materials cost and maintaining quality (more parts = more things to fail).  If they needed to go to a Prius-type electric CVT with one planetary gearset and two bevel gears, they would have a lot of surplus labor to pay for and no way to make up the cost of the motors.

That's gotta change, no doubt about it.


Oh also the other reason for the new doohicky is in big trucks made for towing capacity. Hybrud tech realy does no good as far as towing goes as you need a big heavy engine and a big heavy truck to tow a realy big heavy thingy. This 6 speed will at least help there.

Until they can get fuel cells going full time then they will be able to gang 4-6 small eletric motors one/two to each wheel and power the lot with a bunch of cheap fuel cell stacks. Say 6 40 hp motors powered by 12-24 small fuel cell stacks...


I'm not sure that CVT is the thing that will save us all, they do have some problems.

I think the action is heading towards automated manual transmissions (AMT). I.e. a "normal" manual transmission + clutch that is operated by a computer controlled mechanism. These avoid the lower efficiency associated with a classic automatic transmission, in fact they are often more efficient than a manual transmission since humans tend to forget what the optimum gear for every situation is. Heavy duty vehicles (trucks, busses etc.) are moving this way in a major way, and it's slowly starting to catch on in passenger vehicles too. At least VW and Reanult sell cars with AMT:s.


Ah dont forget they were talking about heavy trucks and light trucks mainly so ya a cvt wouldnt be an option there.


These transmissions will be used in vehicles from the Corvette to SUV's, not heavy trucks.

There are ways to make a CVT for a truck; I was personally involved with such a project.  But what these things need is both efficiency and a technological bridge to hybrid models; electric CVT's a la the Prius fill the bill, 6-speed automatics don't.


I thought they said they were also gona use the thing in heavy trucks as well.. babble in reading too many damn stories I guess and its all blurring.

The main issue with cvt so far was durablity and max power. As I understood it they had yet to make a cvt that could handle all that much torque.. but then the last time I read up on em was awhile ago.

Did they fix the durablity issue?

Frankly im just praying a damn good battery comes along and chucks all these issues in the waste bin of history.


The use of a variable displacement hydraulic pump would create an cvt for heavy trucks. Some heavy construction vehicles already use this system.


4%? One could save more then that by just making sure that his/her tires are inflated properly.

Sure -- but the two things aren't mutually exclusive. In fact, they're not related at all... so why not have both?

The bottom line is that every improvement in efficiency no matter how small is valuable, especially when the improvements are unrelated and are therefore "additive".

If Toyota wrote a press release explaining how a slight modification of their CVT got an additional 4% energy efficiency and improved performance, we'd all say "that's great." So, I say "that's great" when GM does it too.

Tripp Bisop

Throw in a switched reluctance generator and you're looking at 9%-14% improvement in efficiency for heavy duty vehicles. Anyone know if the auto manufacturers are looking to incorporate SRGs into mainstream or hybrid designs? It seems like a no-brainer, but then I'm not an engineer.


Tripp, that's exactly the sort of thing that's possible after you've got a means of transferring large amounts of drive power via electricity.

A switched-reluctance generator could just as easily be used to replace the hydraulic torque converter, turning slip losses into power.  This power could drive a motor on the output shaft.  When slip gets mostly converted to output power instead of heat, you don't need to accurately match transmission input speed to engine speed and you can use fewer gears and fewer parts (with taller gearing, of course).  Once you've got 50 horsepower going through the electric path, substituting power from the TIGERS for power from the engine shaft would be a relatively small change.


1-2 mpg saving in a 15 mpg tank is irrelevant.

What does not make sence to me is the indolence of management. If they wanted to keep the gargling sound of a v8 which all the rednecks adore, they could make a hybrid v8. That could be both more efficient and more powerful.

With regards to the 50% improvement, of course its possible. You just have to go from 1960's 8 valve pushrod crap to 20 valve VVT hybrid stuff, or turbo diesel of equivalent capacity.

Harvey D

Just another GM-Ford commercial trick to try to convince North American buyers that quality and effciency of their vehicles will increase with one more gear in the transmission box.. Toyota Prius already have 1000 + gears transmission (CVT).

GM and Ford's problems are much deeper and 'gear multiplication' will not fix any of them. They will have to build the right vehicle at the proper price and such vehicle may not even have or need gears.
It is very doubtful if it can be done with the present UAW contract conditions?

GM and Ford may have to do what many North Americaan manufacturers have already done. Move most of their manufacturing activities to China and/or other countries with lower labour cost even if they have to bankrupt the American parent companies and UAW do to it.

Alternatively, UAW could accept a 50% cut in total pay (from $65 to $32.50 an hour) and GM + Ford could innovate quickly, by scraping their gas guzzlers, and becoming world leaders in the production of efficient plug-in hybrids, using their most efficient existing platforms, within 2 years. New light weight aerodynamic plug-in hybrid platforms should be designed and on the market within 4 years.

If both parties are not prepared to make a drastic move, it may be bye-bye to GM, Ford and UAW before the next federal election.


Gm prolly cant make drastic moves they are a very... slow changing conpany at best and weighted down with a very slow changing union its not gona look good anyway you slice it. Ford is however changing much faster then gm but then ford managed to avoid many of the union health care plan pitfalls gm fell right into AND ford made some very important partnerships with japanese companies early on.

The good news is if gm tanks ford will then become much stronger.


Maybe GM can add a second reverse gear, or manufacture some of their 1970's cars new to bring back the nostalgia. 8mpg all the way baby.

Tho, I would love to have a 60's or 70's faux beast. Made of modern lightweight materials and latest hybrid gear, but otherwise completely authentic looking.

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