Originally Posted by Pony Boy
It's impossible to determine if electric vehicles pollute less than internal combustion engine vehicles without considering where they are to be driven and what source of electricity is used to generate power. An electric car that is charged with energy from hydroelectric power, will produce very little pollution, while one charged with energy from a source, like coal or oil, may produce more pollution than an internal combustion engine car.
a.) Producing electricity, even in a coal plant, is far more efficient than producing energy in an internal combustion engine. This is pretty much entirely about gains from scale and using more efficient ways to capture thermal energy that results from burning fossil fuels
b.) Electric cars are more efficient per unit of energy than internal combustion cars, even after the energy is produced.
This is why electric cars have an "MPG equivalent" rating. Tesla is getting around ~100MPG equivalent ratings producing as much or more torque/horsepower as ICE's getting 15 MPG. Once they scale down out of the luxury market, they will likely be getting closer to 200MPG equivalents.