REPORT: EPA planning to address outlandish fuel economy claims of electric cars
The EPA is aware that range-extended electric vehicles can game the current fuel economy test to deliver mileage estimates way up in the stratosphere. It makes for impressive advertising, like General Motors' touting of the Chevrolet Volt's estimated 230 mpg, but the EPA wants to give a more realistic reflection of the fuel efficiency of these types of cars, and it's not alone.
According to USA Today, the National Renewable Energy Laboratory would like the EPA's new formula to provide buyers information about the efficiency of the vehicle on either of its two fuels, providing two different numbers. An Israeli company also wants more data, pushing for three pieces of information: electricity used when fully charged, electricity consumed to top off the batteries, and how much fuel the range-extending gasoline engine uses when pressed into service.
The new ratings are important to consumers and automakers alike. If accurate, these new ratings would give buyers more insight into what they can actually expect to get. For now, carmakers are holding their breath to determine just what they'll be able to get away with claiming when advertising... let the lobbying begin!
[Source: USA Today]
Reader Comments (Page 1 of 1)
nrb 4:48PM (10/01/2009)
Too bad it took something as high profile as the Volt to get this to happen. Absurd MPG claims from EV variants have been irking me for quite some time.
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LeanGreenMachine 5:06PM (10/01/2009)
Agreed - it's like saying I can get a month's battery life from my laptop but failing to mention that I can only use it for 5 minutes a day to get the quoted figure.
Clarity is the only way to go to get Joe public to understand (and thus accept) alternative methods of transport such as EVs, ER-EVs, PHEVs, etc
Mark Kiernan 5:12PM (10/01/2009)
How about cost in dollars per mile? Of course it would change every day but you could have a round figure based on average prices (quoted). So a hummer would be something like 5 dollars per mile while the volt would get .5 dollars per mile.
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KK 5:28PM (10/01/2009)
I think that would be a good start. But the cost per mile would still depend on how the car is used - i.e. whether it's charged every night and driven 30 miles a day, or used on a cross-country trip.
For plug-in hybrids, I think they should quote two numbers: cost per mile when used as an electric vehicle (i.e. generator never kicks in), and cost per mile (or MPG) when used as a series hybrid car (i.e. car is never plugged in).
Boyprodigy1 6:33PM (10/01/2009)
Watthours/mile. Its the best choice. You don't get the cost when you buy a car based on its miles/gallon figure, but you do learn something of its efficiency. This way people could buy the most efficient vehicle and watch electricity prices making it easier to choose what car they want to buy.
Keith 10:46PM (10/01/2009)
It doesn't have to change every day. The EPA could use a standard amount per gallon, say $3.00 and stick with it. The same idea could be used for electricity per kwh. As long as the base costs stay the same, the formula would work. It wouldn't matter if a gallon of gas actually costs more or less on any given day. The standard needs to be set to allow comparisons. Cost per mile is the only way to adequately compare apples and oranges, or in this case, gas, electric, hybrid, diesel, fuel cell, or whatever powered vehicles.
Rick 5:52PM (10/01/2009)
People need a simple number to look at - like 230. There is no way to express in simple terms how much energy the volt will use - Maybe they should advertise volt gas consumption as "whatever you want it to be"
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kert 6:16PM (10/01/2009)
Fuel economy of electrics ?
More important are establishing the certified RANGE standards for electrics, both for highway and city driving.
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Matt234 7:18PM (10/01/2009)
The Israelis are right on the money with this one. There is no way around it: you need more numbers. Anything else will leave people guessing.
But... according to USA Today they say you need "...how much electricity a car uses when it's fully charged, how much electricity it takes to charge the car and how much gas the car uses when it's out of juice". It might be me, but are the first two the same thing?
So... EPA, if you're reading this, what I want are three numbers:
1. Battery capacity (KWh, cost to recharge, or equivalent)
2. Range before needing to charge (miles or KWh/mile, or equivalent)
3. MPG when in recharge mode
If you want to get detailed, #2 and #3 need to be split into city/highway numbers. #2 would probably need to define the lowest charge allowed, e.g. only dropping to 40% before needing to recharge. Actually, while you're at it, turn the numbers for #2 around to miles/KWh.
I credit GM for giving us a new system with the three numbers by making such conspicuous and astronomical claims. Thank you GM (even though I realize it was unintentional).
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GoodCheer 7:47PM (10/01/2009)
I agree that more numbers are necessary, but I would ditch the battery size. Manufacturers will advertise that of their own accord. Besides, the volume capacity of the fuel tank is of far less consequence than the range between fill-ups, so I argue the energy capacity of the battery is not necessary, only the range on electricity.
So in place of the current two numbers (city / highway mpg), I would argue for four numbers much like yours (Matt)
city / highway range on electricity
city / highway mpg in charge sustaining drive
That way people have the usual numbers that we're all familiar with, plus the electric range.
For vehicles that operate in blended mode, then the E-range numbers would simply be the available battery capacity divided by the Wh/mile needed for each EPA drive cycle.
Matt234 7:19AM (10/03/2009)
@GoodCheer. That's a good point. The first number I suggested is really related to cost of filling up, or the time it takes to fill up, but not consumption. Those are numbers I want, but there is no need for the EPA to get into that.
Tony Belding 9:18PM (10/02/2009)
I was under the impression that the EPA rules were *designed* to produce wildly inflated MPG numbers for electric vehicles as a way of promoting them to the public. I remember Tesla complaining that they didn't want to post the unrealistically high MPG numbers on their website, but the law required them to use the EPA's formula.
GM, of course, took the other approach. . . embracing their absurd MPG rating and trumpeting it all over the internet and beyond. Maybe that's what it took to shame the EPA into changing this -- while feigning outrage at GM's "gaming" of the system that the EPA itself had forced on them.
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NorthernPiker 5:39PM (10/03/2009)
To arrive at one number for MPG, one needs to assume electricity rates and gasoline prices to derive a miles-per-gallon equivalent while in electric mode and to assume a percentage of mileage that the vehicle travels in electric mode. A general set of assumptions would be:
1. electricity costs of 10¢ per kWh,
2. gasoline costs of $3 per gallon, and
3. 75% of the mileage as being in electric mode.
First, the energy usage in electric mode and in gasoline mode would need to be measured. For a vehicle the size of a Volt or Prius, 5 miles per kWh and 50 miles per gallon are consistent with numbers that have been posted on the Chevy Volt and CalCars web sites.
Then, moving the vehicle 200 miles, with 75% of the travel in electric mode, would require 30 kWh of electricity, which cost $3.00, or 1 gallon of gasoline, which cost $3.00. The total cost to travel 200 miles would be $6.00, which equals the cost of 2 gallons of gasoline. So, the MPG is 100 miles per gallon. Interestingly, 100 mpg is the average of the 150 mpg in electric mode only and 50 mpg in gasoline mode only.
The 100 and 150 mpg figures are dependent on the ratio of fuel costs to electricity costs, both of which vary but not in the same direction or at the same rate. For example, over the last year, fuel prices have decreased and electricity rates have generally increased. In addition, electricity rates vary widely by region of the US, by customer category (residential, commercial and industrial) and maybe by time of day. Here’s a table of AVERAGE electricity rates for each state - June ’09 & ’08 data.
http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html
In internet lingo, YMMV (your mileage may vary) is a good caveat for one number for MPG. Perhaps, the EPA should publish one number along with the underlying assumptions but supplement it with a web site (or automated voice system) that would generate an MPG figure for specific electricity rates, gasoline prices and electric-mode percentage.
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