Well, its not that simple. As I stated earlier, the coal powered power plant has a 25% efficiency, ie: for every 1 Joule worth of coal that is loaded into the boiler, you get 0.25 J out, roughly speaking.
Then the electrical grid is only about 90% efficient. So that 0.25J is now down to 22.5%.
And the charger and car itself is only 75% efficient. So now you're down to 17% efficiency, from the lump of coal, to actual traction on the wheels.
So if your claim that the ICE gets 18% efficiency is correct, that's actually better than burning coal in a coal-fired power station, and then transmitting such electricity over already overloaded infrastructure.
Either way, there's a huge energy burden involved with extracting the coal from the ground, versus extracting oil from the ground and refining it into something usable in a car.
The biggest gains are still in reducing unnecessary travel (ie: by rationalizing the financial sector and other non-productive uses of resources), and by making existing petrol cars more efficient through the use of diesel enginese.
And air quality?? Not too many places in the USA have that, and the places that do would benefit extremely from other solutions to that. A proper transit system in LA, for instance. More transit in the SFBay area. Etc. Far cheaper than filling the roads with electric cars, that's for sure.
