Life expectancy of a car 150,000 to 300,000 miles [1] Cost of electricity: 6 to 12 cents per kWh [2] Performance of Model S: 300 miles in 85 kWh [3] Cost of Model S: $57,400 to $77,400 [3]

Electricity cost: $2,550 to $10,200 Percentage of $57,400 vehicle cost: 4.44% to 17.77%

There's also a supercharger 'activation fee' for the models that don't have the highest end battery [4] which presumably rolls in some of that cost. So I agree this is probably economically feasible.

Of course, it all depends on what their profit margins are like when they get to serious production, what the charging efficiency is like, how much use Tesla's charge stations get, and how good a deal they can get on their electricity.

[1] http://www.msnbc.msn.com/id/12040753/ns/business-consumer_ne... [2] http://michaelbluejay.com/electricity/cost.html [3] http://en.wikipedia.org/wiki/Tesla_Model_S [4] http://www.teslamotors.com/forum/forums/update-supercharging...