Filed under: EV/Plug-in, Hybrid, MPG, Chevrolet
NY Times analyzes how the Volt might get that 100 mpg sticker
One of the most persistent questions around the Chevrolet Volt - aside from whether or not GM will be around long enough to build it - is the fuel economy rating. The problem arises from the unique combination of plug-in electric drive and internal combustion range extender. The current standard test cycles used by the EPA for purposes of calculating the mileage of internal combustion cars are only 11 miles long for the urban cycle and 10.3 miles for the highway. Both of those distances are well within the 40 mile battery range of the Volt. If the current test procedure was used the car would use no gas and this is clearly not a realistic evaluation.
According to the New York Times, the current plan is to run car through each of the test cycles until the battery reaches the "depletion" point. From this data an equivalent mpg figure will be determined. The Volt will then be run on each cycle in charge sustaining mode to calculate fuel consumption. Researchers from the Argonne National Lab are currently studying real world driving habits to determine a "utility factor" for blending the two figures. It is expected that this procedure will yield a final sticker value that tops 100 mpg. Of course, because all of these choices are somewhat arbitrary, the bickering will surely continue for the foreseeable future.
Gallery: 2011 Chevrolet Volt Live Reveal
[Source: New York Times]
Reader Comments (Page 1 of 1)
Brn 9:26AM (11/17/2008)
Just wonderful. EPA ratings should be misleading.
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Randy C. 10:44AM (11/17/2008)
Somebody smarter than me is going to have to develop a new yard stick for reporting fuel efficiency. There was a recent intense discussion on my local Electric Vehicle Association's mailing list about MPG in Plug-in hybrids. Some were very upset that the distance gains provided by the electric drive were being handed over to gasoline.
If you were driving a plug-in Prius and drove 3 miles then plugged in, drove another 3 miles then plugged in again, drove the next 3 miles then plugged in over and over you would get over 1000 miles to the gallon for 100 miles. Conversely if you drove that 100 miles straight in one day you would get only 44 MPG.
The old yard stick (MPG) worked well because all of the cars ran on a single common energy source. Since all of the cars had the same ratio of wasted energy (80%) to drive energy (20%) a simple MPG statement worked well. Now an automobile with 2 or more power sources, with radically different efficiencies, and one of them not used in the simple miles traveled per energy unit consumed calculation. A gray area is created requiring either multiple efficiency statements or a whole new yard stick.
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Chris M 2:19PM (11/21/2008)
Angel, I've checked out your off-topic website, and found-
They've rediscovered the DC electric motor!
Oh, wait, they've rediscovered the "self-recharging battery operated motor" scam. Folks, this is an old scam that's been done to death, it relys on the scientific illiteracy and wishful thinking of the marks, and that few people realize just how much energy batteries really store, and how efficient electric motors are especially when running without any load.
Throw in a load of bafflegab and a few misleading measurements, and the suckers are hooked!
Notice that the very last line was a phone number for potential investors to call...
ziv 11:15AM (11/17/2008)
I drive about 12,000 miles a year, and I wouldn't use a lot of gas because most days I drive about 30-35 miles. I checked my driving patterns and I will use between 3 and 5 gallons of gasoline a month so I could say that my mpg would be between 200 mpg and 333 mpg. But since that doesn't take my electricity use into account, it would be kind of deceptive for the EPA to state it that way.
Since the car is primarily electric, with an ICE backup or EREV, the EPA should rate it as a
PHEV40 miles @ (200w/mile [city cycle]) + 50/42 mpg (CITY/HWY) on ICE.
Hmmm...
Or maybe not.
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gorr 11:16AM (11/17/2008)
Gm should say how much kw/h of ev including tramway's they crush in the past and how much they sold the patent right of the ev1 battery to chevron oil compagny.
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rob 11:23AM (11/17/2008)
We all seem to function well with the decision process in the current EPA city/highway. For example, my car is rated at something like 28 city/ 34 highway. Historically I tend to the highway average. So I always account for that in my cost of ownership calc. 100 miles at 34 mpg is around 3 gallons at $1.75/gallon...so it's $5.25.
How about 4 numbers (EV Range City/ EV Range Highway/City Gas Mode/Highway Gas mode)? A rating of 50/40/25/30 would tell me that for my 100 mile drive I could expect the first 40 miles under EV and then 60 miles at 30 mpg. My cost is then 2 gallons of gas ($3.50) and the $ cost to recharge the car (I have no clue yet).
Not rocket science, but then I am an engineer....
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Richard 12:49PM (11/17/2008)
I agree, have several lines of consumption based on the miles traveled to that point (e.g. 1-40 miles= ???Kwh, 40+ miles 44mpg). Buyers can figure out their own mileage traveled and hence the end expense to consider.
Tim 12:30PM (11/17/2008)
"the bickering will surely continue for the foreseeable future."
Ain't THAT the truth!
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John Rowell 12:49PM (11/17/2008)
Why should the MPG rating be misleading? They should give it a double rating - one for gas-only MPG and one for electric-only range. It's so simple that way.
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wave54 2:20PM (11/17/2008)
It could get confusing and utterly pointless in a PHEV or EREV if the gas engine cycles on and off to keep the battery pack charged, meaning there is no initial electric-only range.
If I remeber correctly, that is how the Aptera will work. The ICE will cycle on as battery charge becomes depleted. It will be impossible to come up with any meaningful figure to compare against another vehicle, like a Volt that runs on battery until a certain level and then on gasoline.
Boxman 1:37PM (11/17/2008)
With plugins\EREV's likely to become the norm maybe we should ditch the MPG-equivalent measures altogether. How about we just move to a "cost-per-mile" standard? You could give each vehicle two ratings: cost-per-mile (EV mode) & cost-per-mile (gas mode), along with its EV-range.
For a plugin with 40-mile electric range that costs 6-cents per mile in EV mode, and gets 30MPG in gasoline mode (with gas at $2/gallon), you'd give the following rating:
CPM (electric): 6 / 40
CPM (gas): 200
These would be #'s as tested by the EPA, not from the manufacturer, and would be averages based on 45% highway / 55% city driving, which has become accepted as representative of the average person's driving habits.
The only problem with this type of rating system is it would change constantly with the price of gas and electricity, so you'd probably have to include those #'s as a footnote below the rating.
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Boxman 1:42PM (11/17/2008)
Oops my #'s were off but you get the idea...
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cheleball 1:59PM (11/17/2008)
Gah! Don't blend them! Let us see the separate figures so we can actually make an informed buying decision!
When will the idiocy end?
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cazancoz 2:16PM (11/17/2008)
Yah.. I agree that it's really not that big of a deal. Lets look at it from this perspective: the car has 2 driving modes: electric-only and "charge sustaining mode".
Electric-only doesn't use any gas...but uses electricity, so it should say either miles/watt (if you want to be consistent with MPG), or how many watts used per mile.
Charge-sustaining mode gets normal MPG rating.
Very simple.
To some of the above comments:
It's silly to use actual prices in ratings because prices fluctuate ALL the time.
It's also silly to say "how much for 100 miles". Well.. other ppl's magic milege number they like to consider may be 125 miles. So that would we useless for some people as well.
If I remember correctly the battery is 16kw, but 8kw usable?
So say:
(assume fully charged vehicle)
40 (miles) / 8 (kwh) = 5 miles / kwh in electric mode (capacity is 8kwh)
30 MPG in charge sustaining mode
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Petr Buben 7:39PM (11/17/2008)
How simple is this ?! Why is everybody being so confused?
Volt is, or should be - (if oil monopolies won't kill it off, which they are practically already doing) -
1. electric only, 40miles from el. grid - give mph as current costs of grid electricity and gas. for heavens sake is this that difficult ??
2. electric only, charged from gas onboard generator extender engine (after initial 40 miles) - give normal mpg
For EPA, are you dumb inept-by-definitition government bureaucracy (i hope not), charged, or defaulting to, to kill the reason, kill the electric or hybrid car by refusing to admit and state that they are doing 300 mph -100mpg fuel efficiency??!!
thank you.
Viva oil, right? Why is it they will never mention Volt and 150mpg in one article?? Propaganda? Brainwashing? Oilwashing maybe.
www.Aptera.com (see mpg) , www.GM-Volt.com , www.hybrid.nexo.com , www.hybrid.cz
Now corps are out of power, and suddenly, oil is 50% cheaper in 2 months! .. hmm ....market manipulation? market coruption? maybe....
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John T 6:53AM (11/18/2008)
@Petr
Electricity has a different cost in every area so you can't just give it's "gasoline" equivalent cost.
What happens when gas prices go up or down? What happens when electricity costs go up or down? Then your "combined" scheme doesn't work. That rating you give it in Nov may have nothing to to with it's cost in Feb.
And get off the conspiracy theories. If the Volt is dying it's because GM has been run so poorly that it's going to go bankrupt. The oil companies suck and they are greedy, etc etc. but they are not killing the Volt.
Don't you guys ever get tired of the conspiracy crap? I guess everyone just loves to find an evil "they" to blame for everything, but at least use logic.
The oil companies are to blame for lots of stupid things, but at least apply it when it makes sense.
Petr Buben 9:23PM (11/19/2008)
- Il take your point.
You are right, the price of grid electricity does fluctuate.
Average US price is 12 cents per kWh, but that goes from 7 cents in Kentucky to 30 cents in Hawaii.
So the mpg with el cars should really be given in miles per kWh, or, better yet, kWh per 100 miles.
For EPA, they should not try to estimate how many miles people drive el only and beyond the reach of batteries, but simply give these numbers /above/ for all regimes, "el only from grid, and city/highway", "el only generated by extender gas engine generator" and city/highway.
=====
the number for a medium chinese BYD hybrid car is 12 kWh per 100 km normal mixed driving.
the number for BMW Mini el is $3.50 per 150 miles good day driving.
========== is it still difficult? :]
CONSPIRACY theories.
none from me. Im after facts .... and im open to discuss them.
so lets not talk about a controlled demolitions /991/. because thats what it factually was.
Read how they are changing the Volt design, until the initial idea disappears.
Oil companies corrupted the market, so killed the /big/ truck, GM, Ford and Chrysler. Thanks for not arguing this one. :]
I hope you won't argue with the notion that oil interests are keen to slow down alternative fuels, in order to sell more oil. That is logical, that is the business.
thanks
Petr
www.hybrid.nexo.com
Chris M 2:31PM (11/21/2008)
Angel, I've checked out your off-topic website, and found-
Oh great, they've rediscovered the "self-recharging battery operated motor" scam! Folks, this is an old scam that's been done to death. It relys on the scientific illiteracy and wishful thinking of the marks, and that few people realize just how much energy batteries really store, and how efficient electric motors are especially when running without any load.
Throw in a load of bafflegab and a few misleading measurements, and the suckers are hooked!
Notice that the very last line of the article was a phone number for potential investors to call...
Reply