By on July 4, 2011

The transition from exclusively gasoline-powered vehicles to the new panoply of permutations of gas and electric power has not been easy on the old emm-pee-gee. The imperfect-yet-universal (in the US market) measure of efficiency finds itself at a loss to compare an electric car’s efficiency with that of a gas-powered car, and completely falls apart as a relative measure of efficiency between plug-in-hybrids which use gas and electricity in different ways (see the ongoing battles over the Chevy Volt’s efficiency). Into the breach have stepped several challengers to the emm-pee-gee’s supremacy, including the weak MPGe (which was responsible for the Volt’s disastrous “230 MPG” introduction), and the “Kilowatt-hours per 100 miles” measure championed by Motor Trend in a rare display of admirable pointy-headedness. But the Gordian contradiction of efficiency measures is that they must be both accurate and easy-to-understand… and if the MPG’s history tells us anything, it should probably err on the side of the latter prerogative.

Which explains why Nissan has settled on “Miles Per Dollar” as its new marketing-driven efficiency measure of choice. It’s certainly not strictly accurate, as both the dollar and the price of gas fluctuate in value. Oh, and the price of electricity varies dramatically from market-to-market. But hey, that’s what God created fine print (not to mention the term “your mileage may vary”) for, right? Besides, we’re still waiting on a unit of measure that accurately reflects relative efficiency in a meaningful way without making Americans feel like they’re being forced to learn the metric system…

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46 Comments on “What’s Wrong With This Picture: The New Efficiency Edition...”


  • avatar
    HoldenSSVSE

    Into the breach have stepped several challengers to the emm-pee-gee’s supremacy, including the weak MPGe (which was responsible for the Volt’s disastrous “230 MPG” introduction)

    How many times does TTAC plan to repeat this without acknowledging…

    http://www.autoweek.com/article/20090812/CARNEWS/908129995

    The green car mileage race is now under way, and Nissan Motor Co. isn’t impressed by the Chevrolet Volt’s 230-mpg claim.

    The Japanese automaker says its new Leaf electric vehicle gets 367 mpg, or about 60 percent better fuel efficiency.

    “Nissan Leaf = 367 mpg, no tailpipe, and no gas required,” Nissan wrote on its NissanEVs Twitter page after General Motors Co. announced Tuesday that the Volt would score 230 mpg.

    “Oh yeah, and it’ll be affordable too,” Nissan added, in a dig at the Volt’s estimated $40,000 sticker price. Nissan is promising that the five-passenger Leaf, unveiled Aug. 2, will be priced to compete with $25,000-$33,000 mass-market cars in the United States…

    It’s little GM zingers like that, when there are other guilty parties (including a far more egregious number) that bring out the “B” word.

    • 0 avatar
      stationwagon

      I really don’t understand how one can measure MPG’s on a fully electric vehicle. I wish the Nissan Leaf’s 376 MPG claim meant I could put one gallon of gasoline into a a gas-electric generator, plug in a Nissan Leaf, start the generator and that would charge the car enough to go 367 miles, but that probably isn’t the case.

      • 0 avatar

        Little GM zingers like what? I stated that the MPGe failed the accuracy measure, and used an incident that folks inside GM still shudder at the thought of to illustrate its failure. Nissan’s use of the measure was clearly a scorched-earth tactic, aimed at destroying the MPGe’s credibility so as to undermine GM’s effort (a task that didn’t take much work). I don’t for a second believe that mentioning this fact would have had any effect on your tiresome crusade to discredit me as some kind of inveterate GM-basher. The fact that you take offense at my reference to an incident that the RenCen acknowledges was a mis-step in the context of a piece discrediting MPGe rather than GM, proves (in my mind) where the bias here lies.

        I’m losing patience with having to say that I’m losing patience with the “b-word” brigade. You are not my editorial director, and eventually I’m going to start moderating your contributions here rather than wasting everyone’s time by addressing every single one of your attempts to prove some sinister motivations behind TTAC’s editorial policies (without, it must be added, offering a single explanation for why I might be on a one-man mission to destroy any one company, let alone publicizing your own standard for what constitutes “fair reporting”). I’m secure enough in my motivations for running this site in the way that I do to simply refuse to give you a soapbox from which to misrepresent my (and TTAC’s) fundamental inclinations.

        Keep pushing me… I dare you.

      • 0 avatar
        cole

        Ed,

        Don’t be so offended. Engage not the peanut gallery

      • 0 avatar
        HoldenSSVSE

        Fascinating.

        If I speak my mind, I’ll get banned apparently, hence the dare.

        If I don’t reply then clearly your 100% right.

        So I’ll go out on a limb. Having worked for a number of Fortune 100 companies in marketing. You say that Nissan’s claim was “scorched earth.”

        I have never worked at any company where we could launch a marketing campaign based on a total lie as part of scorched earth that legal and corporate affairs would sign off on. There is absolutely no way in my mind that LCA would sign off on a campaign touting 367 MPG unless they had hard data to back that number up (or provided something to LCA to make them happy).

        If I just made up something to scorch the earth against a competitor, and I couldn’t back the facts, figures, user case, benefits, features, etc. up with hard facts. My butt would be fired. If anyone that worked for me did it, I’d fire their butt. I don’t care if it was traditional campaign or new media; the press picked up the story and ran with it like the wind – a simple search will reveal that.

        If I represent pharmaceuticals, and I market a drug that helps grow hair, and say that it works 75% better than any other prescription drug out there, and I’m yanking that out of my rear end, does that mean my competitor, who comes out next week and says, oh ya, our drug works 150% better when they equally yanked that out of their butts somehow gets a free pass because they were just reacting? (I use the example of restoring hair NOT as even a veiled dig – but as an example of something that is not life threatening in the real world, as MPG on cars don’t have life or death implications like cancer drugs – apparently I need to make my intent very clear)

        You wrote a bit later on just today that you looked to the B&B to call you out (your exact words or darn close) and challenge you. Apparently there are topics that are simply not permitted.

        Well – guess it was fun while it lasted – I took the path of speaking my mind.

    • 0 avatar
      Robert.Walter

      Now there’s a declaration of independence if ever I heard one!

      Happy 4th Ed, and to all other “Don’t Tr(E(a)d) On Me Types”!

      btw, what is the “b-word”? I don’t know it.

      fwiw, I think $/mile is a lousy metric, worse than any of the others … because it incorporates a variable factor, namely the dollar, subject to inflation, or manipulation (QE1/2/3?), so the cost of fuel and electricity, themselves being variable commodities subject to inflation, competition, or (egads, we know how true it is) manipulation, totally discredit the idea. the only good, and compariable over time, metrics will demand the use of fixed, non variable, dimensions.

    • 0 avatar
      gslippy

      I read this story as an equal-opportunity pop at the failed attempts to socialize “MPG” ratings for EVs and their variants.

      GM’s 230 mpg claim was enabled by an inappropriate EPA test, and GM’s publicity of that claim with a lighted stage, announcements, and banners was laughable. At least Nissan’s 367 mpg claim was more subtle.

      However, GM, Nissan, EPA, the media, and the public have all been complicit in muddying the EV efficiency story. This latest attempt by Nissan doesn’t help.

      I actually think the current EPA window stickers for the Volt & Leaf do a good job.

      • 0 avatar
        Derby129

        Nevertheless, the 230mpg banner fronted by a beaming Fritz Henderson was definitely a “Mission Accomplished” grade disaster. It was, after all, a figure at which GM arrived, not one that was confirmed by the EPA.

        For Ed to reference this event in his article is not GM bashing or showing bias, he is simply pointing to past events and the difficulty of rating EVs in a traditionally gas powered world.

    • 0 avatar

      Ed is probably more objective than 99.9% of people who read TTAC.

  • avatar
    GMis4GoodManners

    Am I the only one who noticed the Volt missing from this graph?

  • avatar
    gslippy

    Nissan’s effort here is pretty irrelevant.

    1. Many EV buyers don’t care about the math; they just want to be ‘green’.

    2. Any metric using a varying dollar is ridiculous. Subsidizing EV prices makes ‘miles per dollar’ even less useful than it appears.

    3. MPG comparisons for ultra-low fuel consumption vehicles are meaningless. One should just calculate operating costs as if it used no fuel at all.

    • 0 avatar
      DC Bruce

      And let’s not forget that road use taxes are added to the price of motor fuel, but are not added to the price of electricity used to fuel EVs.

      So, in addition to the initial purchase subsidy (to the customer from the US government) there’s also an operating subsidy as well.

  • avatar
    gslippy

    Even the time-trusted “MPG” rating can’t be trusted. As I recall, the means of measuring MPG has been changed a few times over the decades, most recently in 2008. So comparing the MPG of a 2011 car to a 2005 car can’t be done without a significant correction factor.

    • 0 avatar
      Robert.Walter

      maye, but see my comment above, if you tie efficiency to the dollar, you will add in all kinds of variables that will make the whole thing hopelessly useless for making comparisons…

      • 0 avatar
        psarhjinian

        I’m not so sure.

        We already have, for example, Consumer Reports issuing “approximate fuel costs per year” and such. Of course, it’s an estimate, but it’s a more or less internally consistent estimate, and would all the better for making certain factors in it’s calculation public and widespread.

        I think we’re going to have to live with the fact that EV and PHEV efficiency measures are either going to be hopelessly propeller-headed or necessarily vague. Power draw and battery current delivery at a given load and capacity is a hard measure for people to wrap their minds around. Range is less accurate, but easier to conceptualize. Miles per dollar is worse still, but it’s very easy for most people to understand.

        And really, how is this worse than “approximate dollars of fuel per year” or “miles per gallon, EPA”? It isn’t, really, it’s just that we’re used to inherent problems of the EPA cycle, whereas this is new territory. @gslippy is dead right, there.

    • 0 avatar
      Bryce

      Gallon is not an accurate measure its 3.7 litre US 4.5 litres rest of planet

  • avatar
    jonny b

    Call me pointy-headed but I think we should stick with kilowatt-hours per 100 miles for pure EV’s or hybrids that have the ability to run in pure EV mode. It seems dificult to grasp now but as EV’s become more prevalent the public will become more familiar with the metric. It should only take a few years until we all know the cost of a kilowatt-hour the same way we know the cost of a gallon of gas. Let’s invest in accuracy and have a little faith in our collective ability to grasp new concepts.

    • 0 avatar

      I think we should use mpg-equivalent per 100 miles rather than kwh/100 miles, because I think it’s going to be a long time before there are plug-in hybrids and EVs enough for most people to be familiar w/ kwh/100 miles, and that will enable comparison to conventional cars and non-plug-in hybrids.

      I prefer the per hundred miles because I think you get a clearer picture of relaive consumption than you do with mpg.

  • avatar
    Glenn Mercer

    Hang in there Edward N! I share your pain and exasperation.

    I remember reading a lecture by an academic in the UK who pointed out that, sadly, “More disclosure leads to less trust, not more.” That is, as we lose faith in institutions (church, state, Consumer Reports, Arby’s, whatever) and as technology gives us better tools to ferret out hidden linkages among people and institutions (campaign contributions, cross-shareholdings, loaner cars given to journalists, whatever) we enter a spiral where no statement can ever go unchallenged by an accusation of bias, because there is always one more layer of the onion to peel, one more rock to look under. Heck, if you started unfairly PROMOTING GM, you would be accused of secretly conspiring to tear the company DOWN, since “everyone knows” all journalists are biased or have hidden agendas. Next, people will demand to know what cars you have owned in your lifetime, and then what cars your parents owned, and whether the cute girl in the Mercedes service department gave you free mints last time you brought the S-class in for a tuneup. (At which point the Mercedes Mind Control Mints would rewire your synapses to lavishly praise the Shprinter.) At what point are “sources of bias” really just “information I use to form opinions?” Yeah, if a Ford Tempo dropped its entire back axle assembly on the highway once, while I was driving, I WOULD be “biased” against Ford for a time, until I took in enough new countervailing data. (Yeah, it happened to me.) It is a shame, but we’re probably stuck with this atmosphere of Journalism in the Modern World: Always On, and Always On Trial. Regardless, I for one consider TTAC the most unbiased automotive source I know, because, like Mikey in the old commercials, you hate everyone! (grin)

    I am sure a suspicious type is already noticing that my initials are…GM! Obviously this proves something to someone…. wait… Elvis is calling me from my basement, where he’s been living all these years.

    For grins, you should try writing a piece that would be bulletproof against all bias accusations. It would be a real thriller… something like “Today some car companies made some cars. Some of them had different prices from others. Many people liked some of them, others did not. One analyst noted that windshields are made of some kind of glass.”

    • 0 avatar
      Philosophil

      Great post. Six degrees of separation carried to the extreme….

    • 0 avatar
      Dr Lemming

      Your whole argument is built upon a theory that hasn’t been cited. For all we know it was from one of those scholarly journals that receive financial support from George Soros. In that case, everything spewed in that journal must be viewed as part of an elaborate scheme to dupe you into agreeing to a Marxist takeover of America! (snark)

      In this postmodern world, previously unassailable sources of expertise tend to be challenged if they go against a person’s deeply held ideology. For example, we’ve repeated seen here at TTAC how some commentators can glibly dismiss mountains upon mountains of research on global warming. It doesn’t matter if they know jack about the technical aspects of the subject, let alone the many elaborate checks and balances built into scholarly publishing. If some propaganda group for the fossil fuel industry says it’s all a hoax, then the rest of us are complete dupes to believe that the scholarly peer-review process still works reasonably well.

      Paranoia is so widespread today partly because it is an exceptionally effective propaganda tool.

    • 0 avatar
      psarhjinian

      For grins, you should try writing a piece that would be bulletproof against all bias accusations. It would be a real thriller… something like “Today some car companies made some cars. Some of them had different prices from others. Many people liked some of them, others did not. One analyst noted that windshields are made of some kind of glass.”

      Ah, so you’ve visited Autoblog or Autos.ca?

    • 0 avatar
      Ooshley

      One analyst noted that windshields are made of some kind of glass.

      I am sick of this pro glass industry bias. How about giving all the purveyors of transparent polymers a fair go!?

  • avatar
    Ion

    WWWTP? I can’t give Con Ed a dollar to charge my leaf but I can get a dollar of gas at a gas station.

    • 0 avatar
      srogers

      But you can give your utility company a dollar and fuel up at home with electrons, while filling up with gasoline at home is significantly less convenient.

  • avatar
    WaftableTorque

    I can’t even ride a bus for $1. Automotive win!

  • avatar
    Zykotec

    Before I’ve even earned in the extra cost of buying the Leaf, or any other brand new car, I will have 20.000$ to use on gas in my old BMW, which would mean,hmmm…let’s see. 20.000$, at 4$ a gallon is 5000 gallons, and with 23mpg I’ll have driven 115.000 miles before the Leaf has even been started…That’s a 3500lbs car, with 192hp,4wd, A/C, power everything,and leather.
    (well, realistically, I’ll probably sell it within a year anyway, and it would easily cost me 5k in repairs or just break down completely before I could get so far…)

  • avatar
    Bryce

    Miles per dollar is a good measure I can get 1/2 a litre of diesel and go 27 miles easy math

    • 0 avatar
      srogers

      I like dollars /mile too. Actually, I prefer dollars/km.

      I agree that calculating $/km is going to change from one location to the next because of local fuel and electricity costs. But isn’t cost/distance what we’re really want to know when we’re looking at fuel economy? Just because it varies with time and location doesn’t make it any more stupid than mpgs (which half of everyone either can’t calculate or lies about anyway).

  • avatar
    jpolicke

    The batteries in EVs have a finite lifespan. They have warranties out to 100k, which is what the statistics say the OEMs can offer with minimal risk. Point is, these battery packs are going to die.

    I pull into a station, buy about $50 worth of diesel, and drive 500 miles. Then I repeat. Outside of maintenance costs, I pay as I go. Our brave EV driver unplugs in the morning and goes about his day smugly announcing how his day’s commute cost him $1.85 or something. Like most EV drivers he has not set up some kind of fund into which he sets aside savings for the day when the service advisor says: “You need to replace the battery pack, it’ll be $x,000.” Hopefully the dealer planned in advance and has thoughtfully installed defibrillators at the service counter.

    • 0 avatar
      psarhjinian

      Put it this way: current EVs are about forty grand. Do you know what most non-Lexus cars in that price class cost to maintain once the warranty expires?

      For a Saab driver facing a new engine, a Volvo owner looking at a transmission, a BMW owner a cooling system or suspension, etc, etc, that $x000 isn’t unheard or or unrealistic. Meanwhile, we have Priuses that are ticking well past the 100,000 mile mark without drama.

      Electric and hybrid/electric are this decade’s version of fuel injection. Some companies will do it well. Some will do it badly. That doesn’t mean that the technology is inherently unreliable, only that some companies suck at implementation.

      • 0 avatar
        th009

        An inverter for a Prius also costs about $4000. And there is no automatic hand-grenading of BMW or Volvo engines or gearboxes at 100K with proper maintenance.

        Batteries, on the other hand, do have a finite lifespan. Design and usage patterns will influence that, but they *will* lose capacity and eventually become useless.

        I wonder what the remaining capacity is on those 100K-mile Prius batteries.

      • 0 avatar
        srogers

        For my money, I’d be willing to gamble that a Prius battery is no more likely to grenade at 100k than a BMW auto-transmission or a VW diesel turbocharger.

      • 0 avatar
        th009

        @srogers, how long did your last laptop battery last? Or your mobile phone battery? It’s the same Li-ion technology …

        That said, you pays your money and you takes your chances, the choice is up to you.

      • 0 avatar
        wmba

        @th009

        You may have forgotten that both Prius and Volt only use battery between 80 and 30% charge. This is to mollycoddle the battery and make it last. The batteries are also heated and cooled to maintain an even temperature.

        Compared to the way a laptop battery is used, it’s a relatively easy life. GM figures the capacity of the Volt battery will drop to 12kWh after 100,000 miles, but only the 8kWh middle of the as new 16kWh is ever used, so ultimate capacity is not an operating condition.

        Also the Prius uses NMH batteries in the US market to keep retail price down. Other markets get LiOn elsewhere.

      • 0 avatar
        th009

        I don’t forget. That’s one of the design details (and, yes, I can do the same with my laptop battery). But if you only use 50% of the battery capacity, the downside is that you carry around a lot of dead weight, too.

        NiMH cells suffer from voltage depression, too …

  • avatar
    ajla

    The inclusion of the “Hummer H3 V8″ in that comparison chart really rubs me the wrong way.

  • avatar
    Ooshley

    Besides, we’re still waiting on a unit of measure that accurately reflects relative efficiency in a meaningful way without making Americans feel like they’re being forced to learn the metric system…

    If the only thing this EV/Plug-in MPG mess achieved was you lot learning the ‘International System of Units’, coz let’s go for broke and not just aim for metric, I would count it as a success with the added bonus of no longer crashing space probes in to innocent red planets.

  • avatar
    NulloModo

    Why not just go to miles per kilowatt hour? Drivers are already used to the miles per gallon metric (and it makes more sense to me than the liters per 100km that Europe uses, or even a gallons per 100 miles if shifted to our systems of measurement).

    It’s not that hard to find out what you pay per kilowatt/hour in electricity, and the stickers could reflect the US average. According to the Nissan Leaf PR site the average cost to charge it from empty to full is $2.75. The average price of a kw/hr in the US is 11 cents. So, therefore the Nissan Leaf holds 25 kw/hrs of electricity, and with a 100 mile range ends up with a rating of 4 miles per kw/hr.

    • 0 avatar
      th009

      Why does distance/fuel make more sense than fuel/distance? Generally you know how much you drive, I think.

      And due to the inverse relationship, each mpg means less and less as the fuel economy improves.

      • 0 avatar
        NulloModo

        It’s probably just because I’m used to thinking of it in terms of distance per unit of fuel.

        The biggest obstacle to the US adopting the metric system is that everyone is used to the way we do things now, regardless of how much more sense certain metric measurements make.

        Seeing as I don’t think gas powered cars are going away anytime during my lifetime, I’d rather see electric car efficiency measured in a way that’s similar to the way gas powered cars are measured now, and I think it would be a much easier sell to most of the American public.

  • avatar
    NormSV650

    My C5 with 400 horsepower could see 35 mpg purring @ 1300 rpms highway cruise. And I bought it for less than half the price of a new one. My Saturn

    Sky with aftermarket turbo can see almost 45 mpg and it has 350 horsepower. I wouldn’t sacrifce 99 horsepower…

    • 0 avatar
      Bryce

      Nullo we all had the old mile pounds inches system back in the day but even I learned metrics introduced conviniently just after i quit school but its actually easier typo earlier I get 2/3 of a litre for a pacific peso


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