A month ago I wrote a blog post entitled Efficiency Comparisons. I have now added two cars, the Rav4 electric and the Fiat 500e, and also added in a new metric Ton-Miles/kwH.
The Ton-Miles / kwH is an interesting metric. What this metric illustrates is how efficient the technology is to push a vehicle along the road. The Model S is a heavier larger car than all the others. The highest MPGe is the Roadster with a close second the Fiat 500e, which is at least a reasonably attractive car.