I have a vacation house in Chelan, WA. For the first MWh per month, the rate is 2.29 cents/KWh. So, at 330 Wh/mile (plug to car; measuring battery-to-wheel misses the charging inefficiencies) that's 0.76 cents/mile (that's three quarters of a cent, not of a dollar). Even better, it's 100% hydropower, so effectively no greenhouse gas emissions either.