Just to be annoying to everyone, what about other sources of making a car go?
natural gas, propane, diesel, etc? The energy output/creation cost of diesel is different than gasoline so should there be a conversion for a gallon of gas to a gallon of diesel? The other two are gasses so a gallon by volume doesn't mean much without pressure and temperature. Also the same issues as electric are present with the gasses in how you compare to gasoline.
None of them are similar so to get a comparison to compare one to the other is not easy. There are so many ways to measure them. Well to tires natural gas locally here would win since it is just coming straight out of the ground and ran to the houses and a small pump that doesn't take that much power to build pressure slowly and refill the tank. So there is no transmission loss of any sort on natural gas here it would be just the bit of power used for the pump and the engine efficiency.
Pretty much any measurement is going to be arbitrary and can be argued either way so I just say admit it is an arbitrary decision and just explain it as best as possible. I would rather have the top 10 split up into categories just for the people who want to see how good they are doing in relation to similar vehicles(be good for categories and searches). But an overall top 10 is always going be biased and give an advantage to one type of car over the others. I would also say double the pollution output of the coal plant. You guys have no idea how much pollution the mines generate to mine coal. Imagine 50 large rock truck tires dumped in a hole and burned. That is typical for tire disposal
For my car I am not sure if I am even going to bother with measuring electric usage regularly. My electric bill is always the minimum amount and charging the car isn't going to change it so to me it is basically free
