Show me the math for both ICE cars and Tesla, from well-head to road. Because generating electricity takes energy, and there are losses in the distribution system, and the charging systems are not 100% efficient either. Of course, getting oil out of the ground, refining it into gasoline, and moving the gasoline to refueling stations takes energy, too. Show me the end-to-end math, and then let's talk. A 4:1 advantage for the Tesla seems optimistic to me.
I have the same gripe with calling Teslas "zero emission vehicles". They are not. They are "displaced emission vehicles". Of course, it is easier to control pollution at a single point, and pollution controls scale up quite well, so the overall emissions are less for a Tesla versus an ICE vehicle. But don't claim the emissions are zero, they are just someplace else. (And I will grant that there are benefits to simply displacing emissions -- the Los Angeles valley, for instance, is a bowl, and so pollution tends to hang around in the air for a long time certain months of the year. Displacing the emissions outside the bowl has it's own benefits.)