Funny you bring that up, there are those who say that we should figure how much gas is used per mile. You're using all the same caculations, just in a different order. But that's an EPA style calculation I posted.
Oh, and about having that much power in your battery pack: That's the WHOLE REASON that electric cars are a struggle. You take out a 16 gallon fuel tank and put a 370 volt/1,500 amp battery in its' place, LiFePO4 that physical size couldn't cost all THAT much, I'd say you'd be able to build your LA to SF and back on a single charge car that some people could actually afford. In fact if the Tesla Model S really can go 300 miles with the 85kW battery, we'd be talking 2,000 miles, right?
How physically large would a 550kW battery have to be? What would it weigh? (Gulp)
http://www.teslamotors.com/forum/forums ... discussion
We do a lot of conversions when we talk and think about things, personally I really dislike that idea. For example, some parts of the world use a measuring system other than metric, metric is so much better.
Perhaps we stick to watt hours because of how perfectly it defines our consumption per mile. Dividing into quantities of fuel make sense, but for most vehicles that use gasoline, the phrase miles per gallon fits them well. Speaking about traveling 100 miles and how much energy it takes though, it seems silly to me. .36kwh/mi seems like a strange thing to say. But, I suppose it might not really matter as those who understand probably won't be effected to much, the rest won't understand either way, hah.
Anyway, there is no doubt that battery energy density is a really, really big deal and likely the primary choke point that is preventing most people from considering using electric. I have spent some time marveling at how energy dense gasoline is and how pathetic the batteries used in EVs are today. What really blows my mind is the super tiny gain (comparatively) in energy density for lipo comes with a huge risk (compared to some other chemistry) but we go to that length for that little bump in energy density.
This wiki does a good job at putting things into perspective. So many marvel at super capacitors, but look at their energy density, 2% of even our pathetic batteries energy density. Super capacitors aren't so super, in my mind.