"worse polluters than the gas ones"
I'd need to see hard numbers on that. When you start hauling in all the externals, gasoline has a pretty heavy load, too.
The actual calculation would be a tough one, especially if you move past environment-only and start talking economics, politics, and other externals. Electric cars under current power production conditions bring in things like coal mining. Electricity is transported over wires, with losses, but gasoline often moves in trucks. Gasoline cars, you're talking oil wells and spills, and political crap from oil-producing nations.