General Motors study shows superiority of EREVs over plug-in hybrids
Fans of hybrid vehicles have been clamoring for carmakers to add plug-in capability to those models so that they can grab some juice off the grid and leave more in the tank. The problem is that making a useful PHEV is actually not as simple as just plopping in a bigger battery pack and some charging circuitry. Current hybrid models are only designed to run on electricity at light loads and relatively low speeds. At higher speeds or rates of acceleration they operate in a blended mode with both the engine and electric motor running. This of course is still beneficial because it means a smaller less powerful engine is required to meet customer performance expectations while saving gas.
In the real world, PHEVs need more electrical power from the motor in order to actually go farther without starting the engine. A new study done by General Motors using real world data recorded from over 600 cars analyzed how standard and plug-in hybrids would perform in the hands of real drivers. What they found was that to get a real benefit the vehicle needs to be designed to perform at all speeds on electrical power alone. With that much electrical power on board, having a full engine to drive becomes redundant. A small engine to charge the battery however makes sense. An extended range EV (like the Volt) would actually eliminate 70-percent of the engine starts at any time during a drive. AutoblogGreen talked to GM's Pete Savagian about the study and the results.
[Source: General Motors, AutoblogGreen]
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Reader Comments (Page 1 of 2)
Guenther 8:51AM (2/15/2008)
This! is a statistic. Much as a drunk uses a lamp-post, statistics are mostly used for support, rather than illumination.
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Carlos 8:53AM (2/15/2008)
What I've never understood was why no one has done this before? It's a simple basic concept, run an engine at a constant speed at it's most efficient rpm to charge the batteries when needed and when it's not just run off of electricity.
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The Other Bob 9:00AM (2/15/2008)
In the real world Hybrids are not getting the mileage promised because people drive them too hard and the hybrid is not allowed to do its job.
The Volt concept would not immediately kick in it's gas engine for jack-rabbit starts, so would prevent behavior from influencing mileage.
Of course gunning a Volt will reduce its range and cause the engine to start sooner to charge the batteries, but depending on your trip, you may be able to plug it in before that happens.
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calebe 9:00AM (2/15/2008)
I actually think GM is right. The problem is getting the tech cost down where the mass buyer can use it. 35K is to much. drop the price by 15K and it would be a big hit. Until the average middle/lower income person can buy this we are still going to be sucking down a lot of foreign oil.
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Jared 9:02AM (2/15/2008)
Because batteries are large, heavy and expensive and the control system is complex. It is only practical with significant advances in battery technology that are just now being realized (we hope).
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stretchsje 9:04AM (2/15/2008)
Large construction vehicles use a diesel generator to power electric motors. I think the approach makes sense for road cars, too, given this data. Hopefully the constant power source would result in a much smaller battery, only to be used as a power reserve during acceleration. That would result in lighter, smaller, and better handling "green" cars, although the two motors would still be a major detriment.
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Shipey 9:12AM (2/15/2008)
I dunno... they sell an awful lot of cars at the 35K price point with regular engines. The Volt will be fine at that price point, and the tech will get cheaper with time like anything else, at which point it will begin to trickle down to lesser models.
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Brill 9:13AM (2/15/2008)
to the post about price, i'm sure GM is working very hard at keeping cost down, but $35,000 for a car like this, i dont think its out of line. sure 15,000 cheaper and you'd have more buyer, but thats not going to happen in the near future. at 35,000 i'm sure GM is losing money still, but its great PR if they can pull it off, and over time the cost will come down like everything does.
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m 9:16AM (2/15/2008)
Can this really be surprising to anyone? Isn't it just common sense that a series electric hybrid will save more fuel than a parallel system?
Thank you for the newsflash GM. Just release the stinking thing.
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vintage 9:18AM (2/15/2008)
Notice how they don't have statistics like these for their stupid E85 systems. Because E85 takes more fuel to create than it makes. E85 is retarded. I wish the volt was out so they could start pushing that instead of treating consumers like retards and pretending that E85 is green
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YourNameHere 9:33AM (2/15/2008)
im sure a loaded prius is in the high 20s...maybe cracking the 30k mark. alot of the prius you see running around are the tarted up ones alos. i dont think they sell to many base-model ones. if they can bring the volt in at 35k, with remote start and HID lights and all the goodies the prius has they will have no problem selling them. its better looking so ppl that want good gas milage but dont want to look like a nerd while they do it will be all over the volt. good luck GM.
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DKB_SATX 10:52AM (2/15/2008)
Explain to me why the Volt would need remote start... for heating the interior or something? It should be ready to go when you press the on button, unless it has some lengthy "boot-up."
Richard 11:14AM (2/15/2008)
Actually, according to Edmunds, the fully loaded '08 Prius stickers at $26,900 including destination charge. Average sales price is $26,500 and that's fully loaded with the iPod adapter, backup camera, bluetooth, et cetera. Basic models start around $21k.
Joe 9:48AM (2/15/2008)
The battery, the battery is why this has never been attempted. Until recently, it never looked like this could be done because the batteries would have been too heavy. Today, it looks like that hurdle will be eliminated.
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M1EK 10:22AM (2/15/2008)
Don't count the chickens before the batteries hatch. I've not yet seen any conclusive evidence that they've solved the issue of energy density versus useful life.
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LaughingTooHard 11:05AM (2/15/2008)
Hater-ade stock must be booming in a bear market. Lighten up people.
As noted by others, this is just a study showing the positive effects of E-REV on emissions and consumption. Anyone with a working knowledge of if ICE can tell you starting is bad for emissions and fuel economy. Idling is a close second.
Let the automakers make the cars, just try and agree that this study points to a side effect which CAN be beneficial when the cars DO arrive.
Vintage,
Thanks for keeping up the half-truths about E85. Corn based E85, Bad Idea. Switchblade based E85, 3-5 times the energy that goes into making it Not that I want to ruin your hobby of being a naysayer but sounds like you may need to pick a new topic.
http://en.wikipedia.org/wiki/Ethanol
"It is disputed whether ethanol as an automotive fuel results in a net energy gain or loss. As reported in "The Energy Balance of Corn Ethanol: an Update, "the energy returned on energy invested (EROEI) for ethanol made from corn in the U.S. is 1.34 (it yields 34% more energy than it takes to produce it). Input energy includes natural gas based fertilizers, farm equipment, transformation from corn or other materials, and transportation. However, other researchers report that the production of ethanol consumes more energy than it yields. Recent research suggests that cellulosic crops such as switchgrass provide a much better net energy production, producing over five times as much energy as the total used to produce the crop and convert it to fuel. If this research is confirmed, cellulosic crops will most likely displace corn as the main fuel crop for producing bioethanol."
'nuff said.
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vintage 1:23PM (2/15/2008)
Dude. You quoted a research article. As in, something that hasn't been confirmed, and definitely isn't being used right now. Right now E85 is corn based. Also, they use a lot of 'natural gas' to heat up the corn mixture to create E85. Natural gas is a subsidized fuel meant for heating our homes at a reasonable rate. They are using this subsidized fuel, and selling E85 back to us with more taxes. You are paying the taxes on E85 many times more than regular gasoline.
YourNameHere 11:11AM (2/15/2008)
for the marketing material. im pretty sure the prius has it.
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Yar 11:12AM (2/15/2008)
So a small engine to power an electric drive motor? Haven't diesel trains been using that for years?
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why not the LS2/LS7? 1:19PM (2/15/2008)
The Diesel engines in trains are in no way small, and train engines (except for switching engines you've probably never seen) are not hybrids because they don't store energy in batteries or any other form except in the form of Diesel fuel. In other words, they don't have regenerative braking.