This is regional dependent. The last time I looked in Colorado, and electric vehicle is actually spews more pollution when running than a gas car b/c of the amount of coal power plants that we run - much to the chagrine of all the Boulderites in their Teslas.
Colorado is 30% NG and 30% coal, probably because a lot of coal is mined in adjacent Wyoming and MT. The rest are renewables. The coal number keeps dropping, so EV use will improve over time without upgrading the vehicle.