Have you actually calculated the amount of CO2 released per distance traveled for a car powered by gasoline, versus one powered by electricity from a coal plant? If so, I'd be genuinely interested in comparing notes. If not, please sit down and do a quick calculation before claiming electric cars "tend to be far more polluting."
Here's my (admittedly rough) calculation:
Approximately 9.5 L/100km (average for 2015 model year)
times 2.31 kg CO2 emitted per L gasoline burned
= 21.9 kg CO2 per 100 km traveled
17.9 kWh/100km (for the 70 kWh Tesla Model S)
divided by 80% wall charger efficiency (Tesla claims 95%, some users report 80%)
times 0.527 kg CO2 per kWh (EPA average, includes line losses)
= 11.8 kg CO2 per 100 km traveled
Mind you, we're unfairly penalizing the electric car here because we're counting transmission losses over the power grid, whereas we're only counting the emissions from the gasoline already in the tank. A fairer comparison would take into account the carbon involved with gasoline distribution, but that goes beyond something I can easily estimate.
I'll admit I'm not factoring in the environmental impact of battery manufacturing. (I suspect it isn't as bad as the anti-EV crowd claim, since lithium isn't a heavy metal.) Perhaps someone more informed than me can speak to the overall impact of manufacturing an electric versus gasoline car... I'd be interested in reading their insights.