Is the GM Volt mileage claim legit?
WARREN, Mich.--General Motors' announcement on Tuesday that it expects that the Chevy Volt will get an eye-popping 230 miles per gallon begs an obvious question: how can the mileage of electric vehicles be compared to gasoline cars?
It's a problem that the Environmental Protection Agency is working on with the Department of Energy, the Society of Auto Engineers, and California, an EPA representative said on Wednesday. But that system for testing mileage is still in development and not yet public.
The EPA also put out a statement on Tuesday saying that it has not tested the Volt for mileage yet and "cannot confirm the economy values claimed by GM." GM said that its mileage estimate, including triple digit combined city and highway driving, was based on a draft methodology developed by the EPA.
The lack of verifiable tests, however, hasn't stopped automakers from tantalizing consumers. The all-electric Nissan Leaf, due in late 2010, boasts the equivalent of 367 miles per gallon, and the electric Tesla Roadster claimed over 100 miles per gallon mileage as well.
Pressed on how mileage numbers for the Volt were arrived at, GM executives offered some details, saying that the number will vary depending on how far people drive before they replenish the car's batteries.
"I'm confident that we will be in triple digits" with Chevy Volt mileage, said GM CEO Fritz Henderson at a press conference on Tuesday.
(Credit: Martin LaMonica/CNET)The draft EPA methodology figures that a plug-in electric vehicle driver will go a certain number of miles on batteries alone and then another portion on the gasoline engine, explained Frank Weber, the global vehicle line executive for the Chevy Volt. To arrive at the mix between battery versus gasoline, the EPA is studying average American driving patterns, executives said.
The EPA is also developing another, less familiar metric for electric vehicles. In the Volt's case, it will take 25 kilowatt-hours to go 100 miles. Weber said the models behind the EPA methodology are "robust," adding that he expects the EPA to disclose more about the tests later this year.
To come up with 230 miles per gallon for city driving, GM assumes that Volt owners charge the car's batteries once a day, which enables them to do the majority of their driving from electricity drawn from the socket. The Volt, due late next year, is designed to run 40 miles on electric charge and then use a gasoline engine to sustain the battery for longer trips.
Misleading?
Triple digit combined fuel efficiency is certainly impressive--the Toyota Prius and Honda Insight hybrids both sport combined mileage of about 50 miles per gallon depending on driving style.
But immediately after GM's announcement, people began complaining that the claim is misleading.
For example, comparing the Volt to the Prius with that methodology is not useful, argued Darryl Siry, the former chief marketing officer at Tesla Motors and now a consultant with green-tech companies. By the EPA measure, it would appear that the Volt is many times more efficient than the Prius. But the 230 miles per gallon rating more accurately reflects how much gasoline has been consumed rather than the overall efficiency of the system, he said. "People will improperly conclude that the Volt is about five times more efficient that the Prius, which simply isn't true," Siry wrote.
A common way of doing comparisons is converting the embedded energy in gasoline to batteries, which a 2000 Department of Energy rule does in addition to considering the efficiency of the overall energy delivery system.
In the case of the Volt's city mileage, fuel economy will begin to drop off when drivers go beyond 40 miles before recharging. The Volt's electric driving range was chosen specifically because U.S. Department of Transportation research shows that almost 80 percent of Americans drive under 40 miles a day.
In the EPA model GM has followed, those first 40 miles equate to "infinite mileage," since it was charged from the grid and no gasoline was burned. But to consider electricity as infinite fuel efficiency can be misleading given that some energy--be it coal, natural gas, or nuclear--went into the delivery of electricity to charge the batteries.
Observers said advertising the Volt's fuel economy allows GM to bring attention to its products and tout efforts to improve the efficiency of its overall fleet, with one analyst calling triple digit mileage "bragging rights."
Asked whether he thought GM was overpromising by advertising the 230 mileage number, GM CEO Fritz Henderson said no. "We are quite confident under EPA testing methodology, that's what what the customer will see in the city," he said during a press conference, adding that GM is testing the Volt in both hot and cold climates to gauge the sensitivity of the battery system to temperature.
But when it comes down to choosing a plug-in electric vehicle or not, customers need to consider if they fit into the "sweet spot" for plug-in electric vehicles, which is about 20 to 60 miles a day, said Larry Nitz, the executive director of hybrid and electric power train engineering at GM.
"Plug-in vehicles are not for everyone. If you drive long long distances or you can't readily get a charge, it's probably not for you. But if you can get to a plug two times a day, this is a huge huge victory," he said. "It is a far more complicated way of articulating to the customer how much your fuel economy is."
Martin LaMonica is a senior writer for CNET's Green Tech blog. He started at CNET News in 2002, covering IT and Web development. Before that, he was executive editor at IT publication InfoWorld. E-mail Martin. 
The sad part is that GM have a potential winner with the Volt. They don't need these silly claims to make it sound better than it is -- it's already a good car. Just make some reasonable assumptions about city driving, electricity prices, the cost of charging, etc., and then give us an honest assessment of the MPD (Miles Per *Dollar*), and contrast that to a Prius.
GM is actually selling itself short with this rating. They should be telling people that the typical driver won't even use gas 90% of the time they own this vehicle.
BTU per mile is a good measure of energy efficiency, but the ability to use cheaper energy sources (whichever they are) is not a minor advantage.
What most people want to know is estimated cost per mile, right? But that varies enormously. Based on what price for gas? What's your mix of city and highway? How long do you drive every day? Do you charge during peak or non-peak hours?
(BTW, can you program the car to use the cheapest electric rates, or do you have to set an alarm for 2:00 am to go plug it in? )
But don't claim that the volt doesn't get 230 miles per gallon, because it simply does. It is just not an useful data point.
Accurate, maybe, but very deceptive. In that regard, I'd say NOT very realistic because when people see MPG, they think of the amount of gas the car realistically uses, not how much electricity it could use that might free up gas usage. The car probably only gets like 35-45 MPG, but under certain conditions, might not have to use gas so much.
You could probably figure out a way to get 1000 MPG then on the Volt... they just don't tell you that to do it, you'd have to charge it up a couple dozen times in the process while being very careful not to drive over like 40 miles in a shot. To me, that is not at all realistic.
I think electric cars should have to drop the MPG designation, or at least base it on some kind of realistic or standard calculation and then be VERY clear it is just an equivalency and have to state clearly what that equivalency is based on.
If the calculation GM used is really what the EPA is going to use... it is EXTREMELY problematic.
MPG with no recharging would be a better gage of fuel economy. Energy per mile might be more accurate but less useful to Joe Consumer. Miles per KWH of charge? Thats an easy comparison if you just look at the 40. You can combine it with the MPG w/o charging to gage overall efficiency.
Even the prius gets inflated mpg numbers in the city. It suffers a bit on the highway for the same reasons people are dismissing the 230 mpg of the volt.
Yes, but with a Prius (unless they have done a plug-in conversion), the MILES are ultimately coming from the GAS. MPG still makes sense. The Prius really is getting MPG.
The problem here is that they are taking in energy from other sources and then trying to count that towards MPG. But, the Volt isn't getting those miles out of the Gas. That is why it is totally ridiculous and deceptive.
That doesn't change the fact that running it all the time would double my electric bill.
GM estimates it will cost about 40 cents to fully charge the battery. Take that with a grain of salt until its verified, but if it's true that's $0.01/mile! Even vs. something like the Prius and low gas prices ($2.50 per gal / 50 mi per gal = $0.05/mile), that's a big improvement on short trips. As long as it's gas engine is equally efficient when you have to run it (40 miles+), that's a big win!
Now the Volt you plug in. The Prius you don't which does mean the 50mpg for the Prius is a lot more "real".
The 60 mpg Prius claim came from starting the test circuit with a full battery and using that energy to get the car moving. Never mind that you have to keep regenerating that power with gas in the engine, then convert it to electricity--the test is not continual so you use the initial charge as a "bonus" and attribute it all to the gas.
Then of course you have people filling Prius forums wondering why the best they can achieve driving like grannies is 40 mpg. Big oops when you already have diesel VWs getting that, but without a 5k surcharge for a complex and heavy second power system.
With the Volt, they could market it honestly and still sound impressive: Give the honest mileage, 35 or whatever, and mention that X amount of people won't even touch the gas tank going to work all week. Throw in a bonus that for weekend cruises, you'll reach into the gas tank less often so a tankful will last and last.
Must be a flock of Prius owners, Toyota stock owners, and oil stock owners.
Charge the car and put a tank of gas in it and it will get 230mpg
Of course, at the end of the day, who wants this thing? $40k just to start, and who knows what maintenance will cost, along with the inevitable bugs that any new class of product will have. My prediction is that the "green" Hollywood crowd will be paying higher than sticker when it launches, and then prices will drop dramatically as they try to make it a viable product for the masses.
Did you even read the article?? You are making no sense at all..
And btw:
Quote 1: "I love how none of you have ever seen the thing in person and our already making claims."
Quote 2: "Charge the car and put a tank of gas in it and it will get 230mpg"
Have you seen the car? No.. did you just make a claim by your self? Yes..
Does this make your argument useless and invalid? Definitely
Neither that article nor this one addresses that there are many other greener and cheaper means of producing power, notably hydro, solar, and wind. Power in the west is much cheaper than it is in Detroit for example.
Not a Prius owner... no stock... just apparently a bit more common sense and a bit of physics knowledge.
Charge the car... put a gallon of gas in, and it likely won't break 100 miles between the two. 230... impossible in any real-world situation.
The 230 miles per gallon is a hoax and false advertising.
I guess if he had known about them, Mr. Disraeli would have added MPG ratings to the list as well.
If a big corporation like GM says 230, why shouldn't everyone believe them?
What happens to the electric grid if everyone starts plugging these things in?
The electric grid shoult be fine as the cars are normally programmed to charge during off-peak times (when electricity is cheaper in most areas, by the way).
In addition, even the most optimistic plans don't consider an electric vehicle deployment rate of more than 10% a year. And yes, improving the grid to support an additional 30% load in just ten years is quite a feat, but nothing compared to offsetting global warming, fighting wars in oil producing countries and combating terrorism financed by oil money. Expanding the grid is a minor problem and there's enough time.
I agree that it might be that way for a bit.... but... if everyone is charging their cars, they will no longer be 'off-peak' times. The reason for giving the discount will evaporate, and people won't get that deal any longer. The price of electricity would skyrocket unless we could VERY RAPIDLY build utility scale solar and work out our grid to distribute it. People just need to keep that in mind... solvable, yes, but the model is based on the current situation with low adoption.
calexaka, I love the term
As for the MPG, it stands for Miles per Gallon. If you change the formula then you are no longer talking about true miles per gallon. If anything, they need to change the way we rate fuel economy. But to try to convert electricity costs, which varies all across the country, to MPG is like the apples to oranges comparison. It just doesn't fit.
"Note that electric car recharging with electricity comming from coal still pollute less than a gasoline car."
Wrong! Even a GM rep stated that if you charge the car in certain states (e.g. Va was the example), that the coal power pollutes MORE than would the gas (coal is VERY dirty... gas is actually pretty clean in comparison, except for the CO2... but coal is still worse!).
That is a good point... depends on your definition of 'green'. Are we talking about pollution? Are we talking about an heroic effort to limit CO2 because we're thinking about global warming? Are we talking about energy consumption?
Those are all different things depending on your bent on what is 'green' and overall best for the environment. I think most of the electric car push is coming from the limit CO2 camp, not overall good environmental thinking.
monkeyfun14 says "Charge the car and put a a tank of gas in it and it will get 230mpg." Well, you also need to specify how many kilowatt hours of electricity you put into it when you charge it. I need to be able to figure out how much I'm going to pay for electricity as well as gasoline to determine how efficient it is.
Or, they could determine how much gasoline will be used to power a motor generator to charge the batteries overnight, and add that as the gasoline consumed during the first 40 miles, or whatever it actually truns out to be. Who knows, it might take 4 to 5 gallons to charge the batteries over night. That would make for really poor mileage.
I'm a Prius owner, and with gasoline currently at about $2.60, that translates to about 5 cents per mile for gasoline. Government Motors doesn't let you know how much electricity the Volt will consume charging the batteries for use during the first 40 miles, or how many gallons of gasoline would be consumed by a motor generator to charge it over night. The way they are presenting it, it costs nothing.
In another article, I think they stated about 10 kWh of electricity to charge it. They also said about 25 kWh per 100 miles. You can do the math based on that. Certainly cheaper than gas... but it isn't going to get 230 MPG without VERY specific driving conditions... and you're absolutely correct that they are just ignoring the electricity in that.
Here is roughly how they are getting that figure. Let's say that you really can get 40 miles off the charge. Maybe you live 19.5 miles from work and drive 30 miles to Grandma's on the weekend and don't run any errands. Then you would only use a spec of gas all week long and a bit more on the weekend. You'd only run about 1 mile each day on gas, and 20 on the weekend. You'd probably get that and a bit more out of a gallon of gas (which would in this case account for like 250+ miles). I'm sure the EPA has come up with some kind of scenario like this to describe the urban driver. The problem is that the way any normal people think about MPG, this is quite deceptive. It is also slanted at a very particular type of driver. They really need to come up with a rating that more accurately represents electric vehicles. This is a meaningless comparison, and is made to make the electric car look especially good in comparison... which isn't necessarily the case. Don't get me wrong, this is kind of cool technology and is good... it just isn't THAT good.
I suppose you could add a gas motor to an electric car, have a computer fire the engine every 1000 miles and burn off a gallon of gasoline, just so you can say it does 1000 miles PER GALLON.
But its nonsensical, you just have to look at overall costs, and start comparing $ per 1k miles driven...not real cost either or it would unnecessarily fluctuate...just a made up evalutaion number that could then be used to compare cars.
I'm a huge fan of this kind of technology as a hybrid. It is a MUCH better idea than the Prius where the gas motor is the main drive with electric assist. So I LOVE the direction the Volt is going. Using this kind of technology, you could also make a VERY fast sports car that would still have a descent range, capable of also using very little gas under the right conditions. I'd love it. BUT... I don't like the way this is being mis-represented to the public.
I would be interested in this car, but i drive more than 40 miles on some days. I would still be interested if i could go 60 miles round trip and 20 miles of that would be with the generator running and it got 75 mpg. But if it has a tiny tank and only gets 25 mpg with a dead battery then it would be not worth it to me as I have more 60 mile days than 40 mile days.
I would think that they should be required to use a rating similar to the current one that people can identify with. 230 mpg battery / 75 mpg generator or best / worst or something along those lines.
Ummm... where does the electricity come from? Oh, yeah--electric plants that burn coal and other fossil fuels. Not to mention the aging energy grid that would probably fail if only 5% of people switched to plug-in cars.
Because this kind of rating and claims is misleading, and will actually ultimately damage the movement in the long run! Once people buy one and find out they were hood-winked by GM and the EPA, it will sour them on the concept. Give more realistic numbers and then I won't complain.
Something like....
25 kWh average energy consumption / XX kWh/gallon generation from gas (equivalency: 35 MPG on gas only - XX hwy / XX city without recharge - 230 MPG*** possible for average urban driver)
*** (based on limited daily commute and limited additional driving with overnight electrical charging... see epa.gov for more details)
That first number would really be the important one, as it really is the efficiency of the car and the electronic drive/train, as well as the next one to know how efficient the gas generator is. The others would just be to help people in the transition... and the companies should not be able to lead with that final number as GM as done in this ad campaign. They should only be able to use it accompanied by the other numbers.
Cost Per Mile, perhaps? Then it doesn't matter what the source is- fuel, electric, compressed air, whatever. You'd have a real world number to work with for comparison between the different technologies.
a) Miles on one tank of gas (with fully charged batteries) / gallons to get you MPG
b) KWH per full charge.
Knowing that, you can probably make a better informed decision.
"In the Volt's case, it will take 25 kilowatt-hours to go 100 miles." But the battery charge is only good for 40 miles. So, does it use 25 kwh to go 40 miles, or does the 25kwh include the electricity generated by the gas engine?
MPG is a way for consumers to estimate the cost of operation, based on their average mileage and the price of gas. There is certainly not enough information in this article to even make a guess as to what the actual operating costs will be.
I did get a kick out of JHankwitz's interpretation of GM as Government Motors.
It's been stated in other sources that the ICE on the Volt, when running, is good for about 40MPG. Therefore, in a 100 mile trip, you would use about 1.5 gallons of gas, given that your batteries are fully charged first. So that would put us at around 66MPG for 100 miles of flat out driving, however, the 'city' portion likely assumes that you are not going to go over that 40 mile threshold most of the time, before you are able to go home and plug back in.
The main issue with measuring MPG on a gas/electric vehicle is that the sole energy input into the system is no longer gasoline. given the driving patterns of most people I know (including myself), the gas portion would almost never be used, therefore making your MPG rating almost infinite. It seems they are trying to make a 'gas equivalent' measurement to say that 25kW-h roughly equals X gallions of gas in a standard engine, to go the same distance in a comparable vehicle. It's a tricky equation at best, and almost guaranteed to be wildly inaccurate when the rubber meets the road, given the above.
Mind you, going 100 miles on $2 worth of electricity is OK in my books when compared to $10 in gas :)
An electric car does not use gasoline and therefore does not get miles per gallon, period. A bicycle does not get miles per gallon, nor does a horse nor an electric train. Reporters should stop amplifying car makers attempts to confuse the public.
The next claim you'll hear from GM is that they are selling an electric car along with a certificate that somehow "guarantees" that whatever gas is bought for this car, will be generated by anaerobic microbes or some real or imagined zero-impact technology. That is, you get a car and an eco good guy get-out-of-guilt card for one price.
The reality - and what I hope the EPA bases their ratings for electric cars on - is that an electric car's energy source is realistically a continent-size power grid in which all sources - coal, geothermal, nuclear - are essentially mixed into each watt-hour that your electric car uses. If customers want to believe their greeny certificate for their household or company claiming that *their* electricity is derived somehow from an island of windmills, let them. But the EPA should not pass on spurious green claims in its ratings - "draft" or otherwise.
It's all about what average means.
- How many KWH does it take to do a full charge?
- How many miles do you get on a full charge (highway/city)?
- When the batteries run down, how far does the car go on a gallon of gas (highway/city)? (Standard MPG measurement or L/100KM or gal/100mi or something.)
I think that about answers this whole "230 mpg" question and puts it into a nice break down that people can understand. I can get my mind around these figures, not "230 mpg", which is absurd. I don't think pinning this to just one number is useful.
Aptera went for the curve. That also makes sense (but would not be as clear to me as what I described above). However Aptera seemed to pick an arbitrary spot on the curve and called their vehicle 130mpg or something. GM picked a little earlier on the curve, methinks! :-)
- How many KWH does it take to do a full charge?
8KWh. Note that it only half-cycles it's 16KWh battery system, which is how they can make it last 10+ years.
- How many miles do you get on a full charge (highway/city)?
About 40 for both, depending on driving habits. Probably 5 less if you run the heater/AC.
- When the batteries run down, how far does the car go on a gallon of gas (highway/city)?
Not yet specified, but probably 40-50 MPG.
A car the size of the volt is going to draw 100kw peak and probably 20kw cruising. That means your 8kw-h is going to last for 20 minutes.
I love to hear non-EV people spout off about electric drive cars. Weight means nothing when you are cruising. Aerodynamics is everything. The Rav4-EV gets 3 miles per kWh at 60 MPH. The EV-1 got 4 miles per kWh at 60 MPH due to the lower CD. Both vehicles got 6 miles per kWh at 30 MPH because of lower wind resistance.
One other consideration is affect on power grid. A typical home may normally draw about 500 KWH per month. With a vehicle such as the Volt on all plug in and driven 400 miles per month would add another 100KWH to those houses. Electric power is scare in some areas and may present a problem to wide adaption of all electric vehices.
The other way around might be valid as well: I heard that some Prius owners were able to convert their cars so it can be plugged in. I wonder how Prius plugin will match up against Volt.
I've read if you spend the money (it's not cheap) to turn your Prius into a plug in hybrid like the Volt, you can do pretty dang well. Which is exactly what's creating all the ruckus wiht the Volt.
BTW I am all for GM, whether it is 230 miles or not. It is American car and if nothing it will reach at least 75 miles to the gallon. More than enough. I will not have to sit in a ugly Prius.
- by cyclonica1980 August 12, 2009 4:05 PM PDT
- I will just stick with my plans and go with a Ford automobile. No need to invest in a could be car from government motors.
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