More Thoughts on EV MPG

After several posts yesterday, I rewrote my thoughts on EV's and the new EPA mileage numbers.  I am more convinced than ever that this standard borders on outright fraud, particularly when the DOE published what should be the correct methodology way back in the Clinton Administration and the EPA has ignored this advice and gone with a methodology that inflates the MPG (equivilant) of EV's by a factor of nearly 3.  For example, the list the Nissan Leaf with an MPGe of 99, but by the DOE methodology the number should be 36.

The full article is in and is here.  An excerpt:

The end result is startling.  Using the DOE's apples to apples methodology, the MPGe of the Nissan Leaf is not 99 but 36! Now, 36 is a good mileage number, but it is pretty pedestrian compared to the overblown expectations for electric vehicles, and is actually lower than the EPA calculated mileage of a number of hybrids and even a few traditional gasoline-powered vehicles like the Honda CR-Z.

Supporters of the inflated EPA standards have argued that they are appropriate because they measure cars on their efficiency of using energy in whatever form is put in their tank (or batteries).  But this is disingenuous.  The whole point of US fuel economy standards is not power train efficiency per se, but to support an energy policy aimed at reducing fossil fuel use.  To this end, the more sophisticated DOE standard is a much better reflection of how well the Nissan Leaf affects US fossil fuel use.  The only reason not to use this standard is because the EPA, and the Administration in general, has too many chips on the table behind electric vehicles, and simply can't afford an honest accounting.


  1. David W:

    Can you still edit the Forbes article? Your phrasing is incorrect here:"They did this be dividing the potential energy or heating value of a gallon of gasoline (115,000 BTUs) by the energy in a KwH of electricity (3412 BTUs) to get a conversion factor of 33.7 gallons per KwH."

    That is, it should be 33.7 kWh per gallon, not 33.7 gallons per kWh. Specifically, 33.7 kWh has the same energy content as 1 gallon.

    I do like your refrigerator analogy, though, as well as your overall point.

  2. Robert Beck:

    It that the DOE methodology is correct as regards total fuel efficency and/or carbon emissions (if that is of interest); the EPA method informs the buyer of estimated fuel costs, ignoring all else.

    Different strokes....

  3. Robert Beck:

    Yikes! Sorry about those typos --

    It seems to me that the DOE methodology ...


    ... efficiency ...

  4. Artemis Fowl:

    It's disingenuous for another reason as well. If they think we should only measure how efficiently it uses the energy put in, MPG is a totally bogus number as gallons of anything are never put into the car. If they were desiring to measure the efficiency of use from the "tank" then they'd measure in MPkW.

  5. Jeff:

    I agree with what Artemis said... A "mpg" measure for an electric car is inherently flawed. (Although, Artemis, it really should be "MPkWhr", i.e. "miles per energy measure" rather than "miles per power measure".)

    Car buyers need to be able to calculate the cost of their use of the car. Right now, a person can look at low mpg cars and say "oh this costs more to run than this other car". The faked-mpg doesn't tell them anything.

  6. A Friend:

    The CR-Z actually is a hybrid.

  7. John:

    Nice site.
    When estimating Leaf "mileage" as compared with fossil fuel cars, it appears that everyone ignores the free energy used for keeping passengers warm in winter. Is that right? And then, running an AC system in summer requires an enormous amount of energy.
    Obviously, claiming mpg implies an apples & apples comparison. I'd guess that any owner would need an AC/heat pump to economically achieve comfort in a variety of markets and that using such a system in an average market would move the mpg needle down by 20 mpg.

  8. Sean:

    The NY Times reported that the EPA just came out and validated your analysis in a backhanded way. They reported three mileage numbers to consider for the Chevy Volt are "Driven on battery power alone, the Volt has a fuel economy equivalent to 93 m.p.g., the E.P.A. determined, using a formula that converts kilowatt-hours of electricity to gallons of gas. The Volt’s gas engine was rated at 37 m.p.g.

    The 93 and 37 m.p.g. figures appear most prominently on the window label, while the 60 m.p.g. figure is in much smaller type toward the bottom. The Nissan Leaf, a pure electric car, was rated this week as getting the equivalent of 99 m.p.g."

    Personally, I like the idea of a nuclear or coal powered vehicle. When an electric vehicle's price gets competitive, without all the rebates and government incentives, I'll certainly take a close look at one.

  9. Sean:

    I forgot to leave a link to the NY Times article. Here it is:

  10. MikeinAppalachia:

    The whole point of US fuel economy standards is not power train efficiency per se, but to support an energy policy aimed at reducing fossil fuel use."

  11. MikeinAppalachia:

    "The whole point of US fuel economy standards is not power train efficiency per se, but to support an energy policy aimed at reducing fossil fuel use.”

    Well, yes-but: It is also to reduce imported oil usage. As almost zero oil is used to generate electricity, plug-in electrics will accomplish that part of the policy.

  12. Michael:

    The plug in car faces another hurdle I haven't seen mentioned. More and more jurisdiction are requiring that all electrical in garages be run though a GFCI system. Here in Cincinnati, I've been removing these systems for people after inspection because a wet car will trip the GFCI and kill the electrical to the garage door openers.

    I can see people coming home after work in their plug in cars only to find the GFCI having tripped and the car dead in the morning. Maybe like green energy, people may need to keep a fossil fuel car on stand by.