Mandating Faulty Accounting to Reach Absurd MPG Standards

President Obama wants a 56.2 mile per gallon standard for cars by 2025.  Both advocates and opponents of this say the only way to make this is if everyone drives an electric car or plug in hybrid.  But the fact of the matter is, even those don't get 56.2 mpg, except through an accounting fiction.

A while back I ran the numbers on the Nissan Leaf. According to the EPA, this car gets an equivalent of 99 MPG.  But that is only by adopting the fiction of looking only at the efficiency in converting electricity to power in the wheels.  But the electricity comes from somewhere (the marginal kilowatt almost certainly comes from a fossil fuel) and the new EPA methodology completely ignores conversion efficiency of fuel to electricity.  Here is how I explained it at Forbes:

The problem is that, using this methodology, the EPA is comparing apples to oranges.   The single biggest energy loss in fossil fuel combustion is the step when we try to capture useful mechanical work (ie spinning a driveshaft in a car or a generator in a power plant) from the heat of the fuel’s combustion.  Even the most efficient processes tend to capture only half of the potential energy of the fuel.   There can be other losses in the conversion and distribution chain, but this is by far the largest.

The EPA is therefore giving the electric vehicle a huge break.  When we measure mpg on a traditional car, the efficiency takes a big hit due to the conversion efficiencies and heat losses in combustion.  The same thing happens when we generate electricity, but the electric car in this measurement is not being saddled with these losses, even though we know they still occur in the system.

Lets consider an analogy.  We want to measure how efficiently two different workers can install a refrigerator in a customer’s apartment.  In both cases the customer lives in a fourth floor walkup.  The first installer finds the refrigerator has been left on the street.  He has to spend much of his time struggling to haul the appliance up four flights of stairs.  After that, relatively speaking, the installation is a breeze.  The second installer finds his refrigerator has thoughtfully been delivered right to the customer’s door on the fourth floor.  He quickly brings the unit inside and completes the installation.

So who is a better installer?  If one only looks at the installer’s time, the second person looks orders of magnitude better.  But we know that he is only faster because he offloaded much of the work on the delivery guys.  If we were to look at the total time of the delivery person plus the installer, we’d probably find they were much closer in their productivity.  The same is true of the mileage standards — by the EPA’s metric, the electric vehicle looks much better than the traditional vehicle, but that is only because someone else at the power plant had to do the really hard bit of work that the traditional auto must do itself.  Having electricity rather than gasoline in the tank is the equivalent of starting with the refrigerator at the top rather than the bottom of the stairs.

The DOE has actually published a better methodology, going from "well to wheels," creating a true comparable efficiency for electric cars to gasoline engine cars.  By this methodology, the Nissan Leaf all electric car only gets 36 MPG!  In fact, no current electric car would meet the 56.2 MPG standard if the accounting were done correctly.  Which is why the EPA had to create a biased, inaccurate MPG equivalent measure for electric vehicles to artificially support this Presidential initiative.


  1. gordon-bennett:

    What is needed is a measuring system which automatically takes into account all these secondary and other factors.

    Well we already have such a system - the price mechanism.

    Therefore, the target should be cents per mile, not miles per gallon.

    This would also allow the inclusion of depreciation. There's no point in having a car that does 100 mpg if it costs a million dollars to build it.

  2. NL_:

    Rather than worrying about miles per gallon on a car that doesn't use 'gallons' of fuel, I'd rather just know how many miles I can expect an electric to run on a full battery (city miles and highway miles) and how many hours it takes to charge.

    But such practical information for the consumer doesn't translate as easily into a single number that politicians can gripe about and car salesmen can brag about.

  3. Sean:

    It gets sillier than that. The auto companies are lobbying hard right now and they are designing in the loopholes as we speak. My favorite is this from yesterday's WSJ, "The administration also agreed to make it easier for auto makers to meet the new targets. It has agreed to give credit to auto makers that include advanced air-conditioning systems that use refrigerants that emit less greenhouse gases. The credit could effectively lower the target by 6 miles a gallon, and reduce the per-vehicle cost of complying with the standards by $1,100, according to one industry estimate." And remember the flex fuel standard? The biggest vehicles like the Suburban and Excursion were all designed to run on E-85 so they would be exempted from the old CAFE standards. The government shenanigan machine doesn't just run on batteries.

  4. Steve:

    All this genuflecting to the environmental gods is getting me down. I say we should band together and sue the government for not separating itself from the religion of "E"nvironmentalism.

  5. Dan:

    This is a good post and I agree. However, electric cars do have advantages that the post doesn't acknowledge.

    Electricity to run an electric car can be generated from a number of different sources, including natural gas, wind, oil, hydroelectric, geothermal, nuclear or solar, many of which are abundantly available right here in the United States.

    Gas-powered cars can only use oil, much of which comes from unstable places like the Middle East, Africa and Venezuela, where oil revenue supports dictators and terrorists and where we spend untold billions of military money defending the shipping lanes to get oil from these places back to the U.S.

    Your description doesn't take those geopolitical and economic costs into mind.

    There's also an environmental benefit in using electricity from less-pollutive fuels like natural gas to run electric cars. I know you're not a believer in global warming, but that aside, I think everyone can agree that it's healthier to breathe air that's not polluted by oil refineries. Natural gas drilling isn't necessarily clean, but most scientists agree it's cleaner than oil.

    Also, conventional oil supplies are peaking, and it's unclear if supplies from oil sands and below the ocean floor can make up the gap in an economical way (the current near-$100 oil prices are a good sign that the answer is no). Better to get our power from a variety of fuels rather than be dependent on oil. The competition from these other fuels will also help to knock oil prices down, which is good for the economy.

    Your analogy about the refrigerator delivery is very entertaining and makes sense. However, be careful not to come out looking like a shill for the oil industry.

  6. Ted Rado:

    The figures are actually worse than Warren describes. Thermal power plants have an efficiency under 40% (for fundamental thermodynamic reasons). To charge the battery, applied voltage must be higher than the battery voltage to make the current flow. When discharging the battery, voltage is less, also to make the current flow. Thus the charge/discharge of the battery might have an efficiency of 85-90%. There is also the loss in distribution of electricity to the charging station.

    If you run the numbers, by the time you generate electricity in a NG fired boiler, distribute it and charge the battery, the overall efficiency is not much better than burning the NG in a NG powered internal combustion engine in the first place. All at much increased cost and complexity. Only nuclear avoids this problem. As has been pointed out many times, by the time standby power is factored in, wind and solar gain nothing.

    Another point is the availability of NG. There is stated to be over 100 yeras supply of NG. If we double the consumption, this drops to 50 years or so and we are right back in the glue.

    A TOTAL package must be developed, not just a piece of it, which can be very misleading. If we make big changes in our energy system, lets get it right.

  7. CT_Yankee:

    So will the MPG be measured with real gas, or with the newer "energy lite" ethanol, which many vehicles find "less filling".

  8. Dan:

    I'm not against a combustion engine in the car powered by NG. What Ted says is right, of course. If we start using NG for transportation, its supply timeline is cut in half.

    My hope is that within 50 years nuclear fusion will solve all of our energy problems. I wish the government would spend more on that.

  9. anon:

    "Electricity to run an electric car can be generated . . . "

    Nice platitude, but the question is "is generated" when it comes to MPG ratings. There, your choices are coal, nat gas, nuclear and a a bit of hydroelectric.

    Everything else is round-off error.

    So take a weighted average of nuc, hydro, coal, and nat gas to determine the BTUs needed to generate each kw-hr, and then subtract for transmission losses (not all that big). Answer comes out right about where where Warren put it.

  10. Dan:


    I wasn't commenting on the MPG standards and didn't try to figure out the answer to that. Just trying to say electric cars make sense for reasons beyond MPG.

  11. Tim:

    I've responded to this before -- The EPA and DOE numbers measure two different things; which is why they use different methodologies and get different results.

    In summary, the EPA numbers measure the overall efficiency of the vehicle -- how well it uses its stored energy. The DOE numbers look at the overall efficiency of the system; and use the EPA mileage as the baseline for the efficiency calculation.

    The EPA numbers are for comparing the relative efficiency of cars; the DOE numbers are used to calculate the mileage for a particular car to be included into the CAFE calculation.

  12. IgotBupkis, President, United Anarchist Society:

    >> Which is why the EPA had to create a biased, inaccurate MPG equivalent measure for electric vehicles to artificially support this Presidential initiative.


    >> What is needed is a measuring system which automatically takes into account all these secondary and other factors.

    What's needed is a method for introducing lead into the skulls of the kind of lying, agenda-driven hacks that create these abortions.

    I recommend steel jacketing the lead as a first step...

    >> I’ve responded to this before — The EPA and DOE numbers measure two different things

    No SH** Sherlock!?!?! Whodathunkit?

    The problem is that your argument doesn't mean JACK SH**.

    "The EPA numbers are for comparing the relative efficiency of cars"

    Really? So the Leaf gets 99mpg compared to my 300z's 16mpg? It doesn't offload most of the fuel expense into the electrical infrastructure -- it actually uses ONLY that fuel amount to go 99 miles -- a gallon of gas or its equivalent?

    Really? Are you certain?

    Truly Certain?

    Can I hack off your arm if you're wrong? Because if "no", then you're not particularly certain after all... :-S

    The numbers are freakin' garbage, and have no business being stated in any conversation together with MPG figures for conventional vehicles -- they are an intentional lie/obfuscation by knowing parties who, as noted above, ought to be shot.

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  14. Gaulnilo:

    You have to remember that this is the same government who, when faced with the issue of putting octane numbers on gas pumps, had to decide the issue of using the Research Method or the Engine Method of measuring octane. The numbers differed by about 10 points. The numbers we were used to were the higher one, which one I forget. (I think it was the Research Method)

    The bureaucrats after much heavy thinking couldn't make up their minds, and mandated that an average of the two numbers be used. (remember the little equation that pump octane = r+m/2 on the gas pumps) This meant that you could not compute pump octane directly, but had to do both tests and average them to find the answer.

    One result is that the pump octane numbers that came out were on average 5 points lower than the octane numbers we were used to for the same grade. I bet today most people believe that octane dropped dramatically when unleaded was introduced. In fact they dropped only a few points from the 95-100 old octane figures we were used to.

    I would bet that at gunpoint the idiots involved could not define what octane measured.

  15. Tim:

    Here's the point between the two numbers:

    The EPA number shows how, for a given BTU equivalent; an electric vehicle would travel. It allows a fair comparison between different fuel technologies. The assumption is, starting with a full battery charge, a Leaf would use as much energy as a 99MPG IC engine car. Note that in any EPA number; there's no account for the energy cost to get the car fueled *OR* charged.

    The DOE number, which is the one *actually used for CAFE calculations*; normalizes the externalities of electricity generation so the fleet average isn't skewed. But even the DOE number doesn't take into account all of the externalities, for gas or EVs.

    If you think you should use the DOE adjustment for non-gas vehicles; then why not use the same methodology for gas vehicles? There's a non-zero energy cost for converting crude into gas, why not round down the window stickers for traditional vehicles, too?

    In summary, the usage for the EPA number doesn't need to account for the externalities; the usage for the DOE number does.

  16. Sam L.:

    I am shocked, shocked I tell you, to find out that my government is falsifying the numbers and the calculations.