Serious question: unless all the electricity for these vehicles comes from completely renewable and environmentally friendly sources, won't banning fossil fuel emissions from motor vehicles just externalize this pollution onto electric power plants? Is there data to show that the environmental impact will be somehow lessened?
People living in an areas that get all of their electrical power from coal need to be more careful about choosing the better option, though. In those cases, something like a high-efficiency hybrid may currently win.