I don't think they should call a vehicle that only gets 21 mpg "green."

It's greener than it was before ...

The problem is GM believes that the hybrid system is best bang for the buck in their larger vehicles. Fallacy of that is the majority of people who would consider the larger vehicle really didn't care about the environment in the first place(or recently converted to the environmental view) or cared about the price or the gasoline, so it really isn't for people who want the highest mileage possible which would be from a smaller vehicle. They really should try to put it into smaller regular cars/sedans to get the green dollar if they are really interested in trying to get it.

aym,

I agree ... mostly. I think drivers of large vehicles do care about fuel costs and about the environment, just not enough to compromise their other desires. In the end the effect is the same.

GM is using the two-mode system to play defense. Their bread and butter comes from large vehicles; they want to protect that market. I also would like to see their hybrid tech put into smaller vehicles. Hopefully that's phase two of their plan.

"Hopefully that's phase two of their plan. - JamesEE"

And by the time they get to phase two, Toyota and Honda will be on phase three.

GM hasn't been a technological leader in a while, exception being the Volt (possibly), and the EV1. So this is a positive development. I just hope they push this two mode system to get better than 20 mpg. If the H2 and H3 get Two-mode GM will actually be a markedly less self-destructive influence on the US. Let me dream.

___I wonder if AM General and GM considered a modified versions of the 2-mode system for military trucks. The high costs of the wars (OEF, OIF) are in large part due to the high cost, and consumption, of fuel for operating medium and heavy wheeled vehicles. GM already has experience with hybrid buses. Oshkosh and BAE also have their heavy duty hybrid programs going. Increasing the fuel efficiency (5-15%) of these cargo/people movers could save billions on fuel. Reducing the demand for fuel will also result in fewer supply convoy runs, which may decrease the overall risk to diesel tankers crews and their escort them, thereby saving lives (and limbs, brains, trucks, money, etc).
___It would also build up a base for medium and heavy duty hybrid component suppliers for civilian vehicles (5-80 ton Max Gross). BAE is already using variants of their HybriDrive for Orion buses and prototype military vehicles.

Personnally I doubt that these so called "two mode hybrid" outperform the Toyota drivetrain. I think it is just a way of differentiation to avoid infringing Toyota patent on hybrid approach.

Will see,

Anyway it is not with such monsters that burn 20MPG that america will get away from its oil addiction.

Last week, the CEO of Chevron, aknowledged that the peak oil will likely happen around 2020, he agrrees in that regard with CEO of Total. But still GM keeps going on "business as usual". That is truly remarkable...

Dang, left a few words in after revision.

@Treehugger.

The method of operation of the two mode transmission is fundamentally different and substantially more efficent than the Toyota at high loads and speeds. Whereas the Toyota always sends energy through an electric path, the two mode alternative can operate as a hybrid OR as a conventional geared transmission. In that mode eg at highway speeds in a heavy vehicle or when towing, a mechanical transmission is far superior to a powersplit one.

Enough of this "designed and made in the US" nonsense. The two mode tranmission is developed as part of a CONSORTIUM featuring both BMW and Daimler. All of whom are interested in a RWD hybrid solution. The idea that this is some sort of "flag waving, save America from foreign oil dependence" solution by GM on its own is just that. Marketing and pandering to the flagwavers.

"And by the time they get to phase two, Honda and Toyota will be on phase 3".

Honda and Toyota aren't even at Phase One for vehicles of this size. I don't think either Toyota or Honda are working on Hybrids for their Pick-ups, unless it's a classified sort of thing.

I think these 2-modes are a good idea for a class of vehicles that are popular and useful to a lot of people. It gives people that would buy a vehicle of this size anyway, a choice for a more fuel efficient purchase. And going along with what JamesEE said, I too would like to see these go in their smaller vehicles as well.

Toyota's rear wheel drive hybrid platform in the 600h is equally applicable to a full size pick up should they choose to go that way.

Toyota are ensuring that there hybrid technologies are placed in market segments where they will command a premium price. I doubt very much that that includes the NA light truck sector where prices are very competitive.

Toyota can afford not to do this whereas GM et al cannot, as their company profit stream is not largely dependent on selling such vehicles.

GM is coming out with a modified version of this in the Vue in 2009 with FWD. The next step is to put it in the GMC Acadia, Buick Enclave and Saturn Outlook [GM I hope your reading...]

For you sceptics, calculate a 40% improvement in City driving for a Chevy Tahoe that a soccer mom drives in fuel savings and polution and it is huge. Then compare the saving from driving a Prius around the city vs a Corolla 4 cylinder ICE and the savings are nill. The vehicle can also run in all elctric mode for about 2-3 miles if driven reasonably.

Plus, can you imaging the vehicle can go to a Home Depot and carry stuff home, the vehicle will have a 110 outlet to for guys that will use it as a work truck, and you can modify this to be your backup in an energy outage at home.[I know the libs out there hate big box stores such as Home Depot and Walmart so substitute Gucci and Prada instead]

1st of all, Toyota and Honda are NOT in the same plane.
Toyota sells 6 Hybrid models with monthly sales above 20,000 while Honda sells 1 model with sales below 2,500.

Between Honda and Ford, Ford is not far behind selling 2 Full Hybrid models (Escape & Mariner).

Hope GM scores with these. Again it depends on the pricing and also the gas prices at that time.

@tree hugger,

Engineering efficiency is incontrovertible to any trained engineering or scientific mind. Questioning its improvement over HSD, is like questioning what happens when you step off a cliff or expect water to run up hill. HSD was designed for the Japanese environment with much more low speed urban driving. America has much more Interstate highway type driving environments.

The 600h is NOT a work truck propulsive system. It is a high horsepower, relatively low rpm limited torque capable design, that is particularly unsuited as a low engine speed, strong torque environment. Its high torque numbers occur at higher RPM.

Toyota will certainly make advances in its hybrid designs; they will need to do so, to match dual mode drive, which is a generation ahead. GM and Chrysler have committed to dual mode applications in autos as well. BMW has already pre-announced dual-mode hybrid big sedans like the 600h. Front wheel designs for the transmission has also been committed all along.

I would expect Chrysler's versions may show front wheel drive applications first for its Minivans; after the SUVs, as GM seems to be choosing the Volt Series electric designs for it electric autos in preference.

Ruaridh, Sorry but this is pure made in the USA - GM invented it here, and pioneered this approach for city buses, and invited DCX and BMW in to share costs and cut financial risk linked to uncertain volumes. GM had this announced and patented before the others were invited in. GM holds almost all the IP rights on the two-mode. Engineers from all three firms are co-located in suburban Detroit

OK ok if everybody is so bullish about this dual mode hybrid I will be more than happy to see that it performs better than the toyota system on higway...well I currently does 50MPG (measured on the pump, not on the onboard computer) on the higway with my prius. Will see how long it takes to GM to achieve the same...franquly I think that dual mode or not there is no way you can get good mileage on the higway with a heavy car and a poor drag together with a big engine and GM is just doing the wrong thing to put hybrid on heavy car with big engine gives little improvment, and this has been reported in a previous post on this site. By the way according to the new EPA calculation the prius return 46 MPG the best non hybrid is the Honda Fit and return 34MPG and that's category of car below the prius, well we are in the 50% improvement overhaul here and almost 100% in city far better than the 40% claimed by GM in the city.

But will see

Ruaraidh wrote: "The method of operation of the two mode transmission is fundamentally different and substantially more efficent than the Toyota at high loads and speeds. Whereas the Toyota always sends energy through an electric path, the two mode alternative can operate as a hybrid OR as a conventional geared transmission..."

In the Prius, the electrical path is but 1/4 of the direct mechanical torque. In larger HSD, like the Lexus 400h, there is another gear stage connecting the generator to the power split planetary, such that the electrical path is further reduced to ~1/8 of that of the direct mechanical torque. At low generator-motor output, the efficiency can be as high as 95% x 95% x 95%(power inverter)= 85% efficiency for the generator-motor route. Take 0.15 x 1/8= 1.8% of overall loss via electric route. Considering that the planetary gear is at near lockup during cruise, hence almost no internal friction, then the larger HSD only incurs ~2% efficiency loss.
I don't think that there is any other transmission that can beat this efficiency level, geared or otherwise!

1) The dual-mode, compound-split hybrid was originally engineered around GM's Allison transmission, for use in hybrid busses. It's been on the road since 2001. It's been mated with diesel engines from a variety of manufacturers - which shows how flexible this design is - and why it was so easy to get DCX and BMW on board.
2) The intent was to get the system on the road into the biggest vehicles first (and the ones that will benefit the most) and work downward from there. Expect this hybrid system to work into the crossovers next and cars sometime after that. The success of E-Flex may change this roadmap. GM currently is planning a multi-pronged 'attack' on fuel-efficiency that includes diesels, mild-hybrids, full-hybrids, and E-Flex (Chevy Volt).
2) You are correct that GM owns the patents and DCX and BMW were invited in on the process to share costs.
3) The dual-mode system in the full-size vehicles are engineered around a four-speed transmission, but the that thought is a bit misleading. The best way of thinking of how it works is this: the combustion engine is bound to the mechanical-path, fixed gear set, and either one (or both) of the smaller electronic engines can upwardly adjust the output from there - so you end up with something very similar to a CVT.
4) GM has designs on a quad-mode hybrid. Shhhh! You didn't hear it from me!
5) GM is currently running mules around the Detroit area (the E-Flex powertrain in a Malibu body). Obviously, GM has already taken possession of the prototype batteries - the supposed holdup in this process. GM is also taking up bids on the tooling for the plant to build the Volt. Forget what GM's history has lead you to believe, the Volt *is* coming.

Yes Roger but a PRius is not a heavy truck powertrain is it? The whole point about the electrical path losses (and I don't think your numbers are pessimistic enough) is that they will get worse as torques increase.

Hence why the 2 mode transmission has so many advantages in that application.

Of course, sorry folks I'd forgotten about the Allison transmission from a while ago. My bad.