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GMC Yukon Hybrid
GM brings hybrid technology to a larger class of vehicles

While most manufacturers efforts with hybrid vehicles have been limited to compact or mid-sized cars, there have been production hybrid vehicles available in larger packages. Ford has the Escape Hybrid, while GM has the Saturn Vue Green Line. For those looking for an even larger vehicle, Toyota offers the mid-sized Highlander Hybrid crossover complete with third-row seating.

General Motors is taking its new dual-mode hybrid technology to an even larger class of vehicle: full-size SUVs. GM will make its new hybrid system available on the Chevrolet Tahoe and GMC Yukon SUVs in 2008.

GM is currently gearing up for pilot production of its hybrid SUVs at its Arlington plant. These pilot runs will give GM a chance to work out any kinks before regular production takes place in the summer.

"We'll do a block of 12 [vehicles] starting at 6 a.m. on Tuesday," said Arlington plant manager John Dansby. "We'll have them spaced out over two days. We'll do a few during the day and some at night so both shifts get a chance to work on them."

The dual-mode hybrid Tahoe and Yukon are estimated to get a 25% boost in fuel economy over their traditional internal combustion engine (ICE) counterparts. That would put their fuel economy at roughly 20/25 city/highway.

GM expects the price premium for the dual-mode system to be in the $2,000 to $5,000 price range. Given that the average transaction price for a Chevrolet Tahoe is already over $42,000, an extra few thousand bucks might be worth it to customers looking for a few extra MPG.

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just an observation...
By Moishe on 3/15/2007 6:55:56 AM , Rating: 2
I find it interesting that:
1.) people want more fuel efficiency
2.) people complain that the auto makers are not doing enough
3.) GM announces a test run of a vehicle that will be 25% more efficient and pushes forward the "green" theme in general
4.) people complain because GM isn't doing enough

Does anyone see the irony in that?




RE: just an observation...
By kkwst2 on 3/15/2007 7:19:41 AM , Rating: 5
No.

The point is that the hybrid concept in it's current state is a joke. The cost doesn't justify the benefit and it distracts from focusing on real solutions. Add ethanol and hydrogen fuels to that list.

Improving diesel engines and working on pure electric cars or hybrids in which the gasoline engine charges the battery instead of these silly dual-drive systems - these are where there is some hope of significant change. Maybe biodiesel, but this is controversial.

Excuse us if we don't get excited about another bandwagon hybrid.


RE: just an observation...
By semo on 3/15/2007 8:15:20 AM , Rating: 2
i think today's hybrids are a joke. if they were so efficient why don't they use them on trains? diesel hybrid trains run the ice at a constant rpm to generate electricity for the electric motors. surely that's more efficient than having a parallel system. why have 2 sources to turn the wheels. it's redundant.

that concept from gm is more exciting: http://www.dailytech.com/article.aspx?newsid=5605


RE: just an observation...
By Compu on 3/15/2007 4:40:11 PM , Rating: 3
The reason why series hybrids are used in trains is not the high efficiency. Series hybrids in trains are used because the electric motors have very high torque for a relative small engine. This high torque is needed for starting the train (a train with 20 wagons of 50 to 100 ton requires a huge amount of torque). Once the train is on cruising speed, it only uses a fraction of the energy requirement for starting it.

The series hybrid has important converter losses: running a diesel engine at constant rpm has about 40% efficiency, coupled to it is a generator with about 95-98% efficiency. Next stop is the AC/DC converter, followed by a DC/AC converter. This conversion is needed to control the frequency of the secondary AC side, namely the engine, as most engines are induction motors (historically there are quite a lot of DC drives, which are controlled through voltage regulation, but have maintenance cost issues due to the carbon brushes). So these two converters both work at 98-99%. And finally there's the engine, again, 95-98%.

This results in 37.6% efficiency on the high side, or 34.6% on the low side. Remember that these are very large engines and converters and size does matter in engineering. For smaller applications, such as road vehicles, the efficiency of every compononent drops even lower. Series hybrids are however the only option for plug-in hybrids to work properly.

Parallel Hybrid use the electric engine to complement the gasoline or diesel engine in the regimes where they perform the poorest, namely the starting/stopping cycle. Here these conversions also appear, but most of the power is transferred directly through the drive shaft. A high quality engine is not characterised by the maximum power/torque output, but how much torqe is available at different regimes outside the optimal point (i.e. how much % in performance do I loose when I'm not running in optimal condition).

This means that the electric engine is mostly used for starting, it is run as a generator to charge the batteries while cruising and absorbing the 'free' energy while braking


RE: just an observation...
By marvdmartian on 3/15/2007 8:46:44 AM , Rating: 3
While I agree with your point about hybrids in their current state, especially for suv's, is a joke, the blanket statement you make about ethanol & hydrogen is just plain wrong.
The problem with ethanol & hydrogen is, again, the current implementation of it. Nowadays, when people hear ethanol, they immediately think of the ridiculous "flex fuel" vehicles on the market now. Unfortunately, they seem to be a necessary evil, to get people to consider alternative fuels. If the ethanol infrastructure can be put in place, like the gasoline infrastructure that now exists, then Detroit could make pure ethanol fuels vehicles (that run much higher compression ratio engines than the current flex fuel vehicles run at), which would get much better mpg on ethanol than we now enjoy using low compression gasoline fueled engine vehicles.
Hydrogen, on the other hand, would be much less expensive to produce from seawater, using nuclear power to provide the electric power to accomplish the seperation of the hydrogen & oxygen.
Improving diesel engines is a great idea, but with the new ultra-low sulfur fuel requirements, Detroit doesn't want to mess with diesel design too much, and is dragging their collective feet on bringing in diesel powered vehicles, due to the redesign of the engine that would be required.
Pure electrics won't be viable until the battery designs get a whole lot better.


RE: just an observation...
By brianvanh on 3/15/2007 9:18:50 AM , Rating: 2
The problem that I have with Ethanol is not so much the MPG, but rather the cost. I live in Iowa (the heart of the corn ethanol movement) and I have a filling station closeby that sells E85 ethanol. What is interesting about it is that the E85 price stays almost exactly .30 cents under the price of gasoline. If gas goes up by .10 cents, then Ethanol goes up by the same.

I'm no expert, but I have a problem with this. Retailers are selling Ethanol for less than gasoline to make it appear to be a value, but when you do the math (after the reduced mpg), you see that it's definitely more expensive to run Ethanol (I think my calculations for my truck are .14 cents per mile for gas and around .17 cents per mile for ethanol...or an 18% difference).

The price of Ethanol should be defined by the price of corn per bushel and not based on the price of a barrel of oil (which is what is happening now). When I see the price of ethanol staying .30 cents below the price of gas, It makes me realize that the retailers are to blame more than anyone. They should be making these fuels available at a price that is more representative of the cost to make the product. I think the retailers are simply using marketing tactics to make a ton of money on Ethanol sales.

If gas goes up by .10 cents per gallon, it would make sense to me that E85 would go up by .02 cents at most because only 15% of E85 is gasoline.

Anyway, as I said....I'm no expert. But I think that the retailers and the refineries are a part of the overall problem. Perhaps just as much so as the auto manufacturers. They could be doing a lot more to make Ethanol a more economic fuel.


RE: just an observation...
By blckgrffn on 3/15/2007 10:37:16 AM , Rating: 2
As a fellow iowan, I think that your point may be valid, but realize that there isn't enough corn to even fulfill the demand for ethanol as is. Keeping the price up on E85 allows the ethanol makers to pay higher grain prices so they can acquire the corn.

What sucks about that is that corn isn't just used to make ethanol, rather it's used for human and animal consumption. Look for higher prices on food in general (meat and corn based products) if ethanol really does drive demand for corn like it has the potential to do.


RE: just an observation...
By semo on 3/15/2007 11:27:07 AM , Rating: 2
sugarcane yields more ethanol than corn. the problem is that the climate might not be ideal and the industry simply won't change if it isn't forced.


RE: just an observation...
By dever on 3/15/2007 1:48:02 PM , Rating: 2
It's hard to know where to start... there are so many ill-informed statements here.

First of all, ethonal costs more than gas to produce. The lower prices are due to my tax dollars being taken from my family and given to Iowa farming companies.

Second, this artificially produced demand for ethonal has doubled the price of corn just in the last 6 months. In yet another way, it's taking more of my money used to feed my family just to pander to a dead-end industry who bought out politicians.

Third, ethanol is unsustainable in it's current form. Even if you slapped the corn flakes out of my kid's hand and forbid me to eat corn-fed beef just to put all corn production towards ethonal, and forced everyone to buy new engines that ran ethanol, we could only supply 7% of the country's current demand for fuel.

Fourth, ethonal has a lower energy density than gas, so you'll get lower mpg.
quote:
Unfortunately, they seem to be a necessary evil, to get people to consider alternative fuels.
Lastly, it's just stupid. Screwing around with markets always proves to be detrimental. People will do what is best for them and their family. As more efficient forms of fuel emerge, the market will adjust. Stop assuming that you know better than everyone else... you don't. You know what's best for you, not for me.


RE: just an observation...
By semo on 3/15/2007 2:28:23 PM , Rating: 2
my post was against corn and i just simply stated a fact that you get more ethanol from sugarcane.

also i didn't suggest all vehicle run on ethanol. fossil fuels have spoiled so many into thinking that you can get all your energy needs from one source. obviously you can't grow ethanol in every part of the world. the electricity from a household socket is rarely produced entirely from a single source. hydropower can't supply the whole world with electricity so why build hydropower stations?

quote:
Fourth, ethonal has a lower energy density than gas, so you'll get lower mpg.
gas has a lower energy density than diesel, so you'll get lower mpg (just thought of mentioning it, not telling everyone to go buy diesel burning cars).


RE: just an observation...
By Playit on 3/15/2007 4:50:22 PM , Rating: 2
A few points worth making...

I actually agree that we shouldn't be using Corn… Hemp would be a much better source of biomass... But a few things are worth considering.

First... Free markets are not always the best method to anticipate change. Investing in alternative resources can lessen the eventual effects of an oil shortage on the nation's economy. While alternative fuels are not economical now, they could potentially be in the future with additional research. We could either try to fund that research directly (which rarely ever works) or "inspire" the market to do so, by influencing the market away from Oil. It's really just a short-term long-term question. I'd actually just prefer higher taxes on oil to have the same effect, but this method can certainly work as well.

Lastly I don't agree that screwing with markets never works. We do so all the time and often to great effect. The uranium market would be a good example. One might also consider the various Air Quality acts. More to the point of this discussion, I'd suggest that the national investment in NASA is a good example of a government directing resources into a field with no immediate economic potential. If we can look at our tax subsidies for Ethanol as an investment into developing future technologies then it might be more digestible.


RE: just an observation...
By fic2 on 3/15/2007 10:38:45 AM , Rating: 2
My problem with ethanol is that it is made from corn when there are more energy rich crops out there. Of course, those aren't sponsored by ADM so aren't used. Basically, the whole corn/ethanol "craze" is because ADM has some of the best politicians that money can buy.

Oh, and if ethonal was closer to it's true price it would be much more expensive. Of course, if gas was closer to it's true price it would be, too.

The best thing the government could do for fuel economy for vehicles is to raise taxes on a gallon of gas by about $0.50 and stop ALL subsudies on gas/ethanol/whatever. Then consumers would not only demand cars that are fuel efficient they would probably actually buy them.


RE: just an observation...
By AGAC on 3/15/2007 10:08:04 AM , Rating: 2
Yes, those flex fuels are a necessary evel. 20 years ago pure ethanol was implemented in Brazil in up to 80% of the fleet. But the price of ethanol was much more susceptible to climate since it is a crop, then people start slowly coming back to gas only. With flex cars you can choose the cheapest fuel but the compression ratio is somewhere in the midle of the ideal (a litle higher than gasoline and a litle lower than ehtanol would require).

The technology for variable compression engines is currently under development and there are a few of these variable compression systems working on tri-fuel (ethanol, gasoline or compressesd natural gas in any proportion).

These engines are extremely efficient and will be deployed shortly. Unfortunately, ethanol or hydrogen fuel cells are still sci-fi in the mainstream market.


RE: just an observation...
By hubajube on 3/15/2007 4:40:01 PM , Rating: 2
You can just use direct injection. That will allow you to raise the compression ratio for gasoline.


RE: just an observation...
By EBH on 3/15/2007 3:29:34 PM , Rating: 2
i agree, plus whats the point of making a hybrid suburban, the weight alone will waste gas

its either a sports car or a SUV, from one extreem to the other


RE: just an observation...
By brianvanh on 3/15/2007 8:36:05 AM , Rating: 2
I agree....I think that progress takes time and that a 25% reduction is tremendous. You aren't going to go from complete oil dependency to complete oil independence overnight. It takes time and is an evolutionary process.

Personally, I drive a large full size truck (flex fuel truck by GM)...I own a farm and I could not do my work without it. Generally speaking, I think that most people who own trucks and SUVs don't really *need* them. But if they are going to drive them, then a 25% reduction will certainly help. Is this where we need/want to be? No...but it's a good start.

If you expect people to stop driving SUVs overnight and if you expect oil dependency to go away overnight, then you are certainly an idealist with no understanding for what it will take to make a practical migration away from oil/gas. It's going to take time and it's going to take progressive companies (like GM) to move these concepts forward. Take this for what it is....great progress towards a long term goal.


RE: just an observation...
By semo on 3/15/2007 11:34:19 AM , Rating: 2
i don't think you can say that these trucks are 25% more efficient because you just added a battery and an electric motor. what are the conditions and assumptions? are those ideal figures or average?

i think once you start cruising on the highway you might actually increase fuel usage since now you have dead weight in the form of a battery and other hybrid components. you can call the prius a city car and assume it will be used in the city but a truck like that probably won't always stay in city.


RE: just an observation...
By Playit on 3/15/2007 4:36:00 PM , Rating: 2
I answered this in more detail below, but the different engine is part of the additional efficiency. That is how they can still be more efficient at higher speeds in some circumstances. To what extent will depend upon implementations. The Ford Escape Hyrbid is actually less efficient at higher speeds (compared to lower speeds) but still better than the gas equivalents at those same speeds due to the improved engine cycle.


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