I have written several articles (here and here) outlining why the EPA's method of giving electric cars an equivalent or eMPG is outright fraudulent. I calculated for the average driver, for example, that the Nissan Leaf's 99 eMPG was actually closer to 36. Why? Well, in the EPA's methodology, the science-based Obama administration pretends the 2nd law of thermodynamics does not exist. Specifically, they assume perfect conversion of the chemical potential energy in fossil fuels to electricity. They also assume zero transmission losses. To rework the calculation, I actually used a Clinton-era Department of Energy methodology called well to wheels.
So here is something I thought I would never write: It turns out the Union of Concerned Scientists agrees with me. Apparently they have used a similar methodology to rework electric vehicle MPGs based on the fuel mix of the power in different cities, rather than an average national fuel mix as I did it. I am not sure how they did the analysis - did they use average fuel mix or the marginal fuel, and if the marginal fuel did they assume the marginal fuel at night or during the day? For example, certain California cities look good with solar use but that does not do anything for typical night time car charging.
Anyway, the problem is hard and I could quibble with how they did it. But the results are telling - everywhere they looked, even in the hydro-powered Pacific Northwest, the eMPG they got was lower than that of the EPA's. And in many cases much lower.
If corporations were using the EPA's eMPG methodology, they would be busted by the FTC for false advertising. It's time to fix this calculation so Fisker Karma drivers can't continue to fool themselves into thinking they are doing something positive for the environment.