It really isnt as complex as you make it out to be. Basically is the power grid more green that the efficiency losses associated with getting electricity to your car instead of creating energy in your car. The answer to that question is that most western grids are significantly more green than that efficiency loss which makes every new EV an environmental winner.

They are certainly far better than hybrids both in production cost and running costs although hybrids themselves are better than conventional ICE vehicles in running costs (but not production costs)