We're doing with electric cars what we did with manufacturing in the 1970s, 80s and 90s. We're sending the dirty part of the process elsewhere. And pretending it doesn't exist.
When EPA, OSHA and labor unions became too onerous for U.S. manufacturing 40 years ago, we started sending nearly all of our manufacturing overseas. The environmental impact on the U.S. was great. No more dirty manufacturing plants in America! But the net effect on the world wasn't so great. Think about how much more world pollution is caused by shipping raw materials to China where there are lax environmental laws, then shipping the finished goods back to the U.S. (Why don't people ever talk about this??)
It's the same with electric cars. If you only consider the car itself, sure it's much cleaner. But if you consider the generation, transmission and storage of electricity it probably causes even more pollution for the world than what we have now. And that's not even considering the manufacturing and disposal of batteries. You can't just crush a battery, melt it down and make a new one like you can with a gas burning car engine.
That said, I want an electric car. They're so cool, and it would make me feel better about myself! And my farts would smell good! (Just like with hybrids 20 years ago.) LINK