I think that the ginormous market cap is due to Musk's PR skills but also, especially, to the fact that Tesla is seen as a cool tech company more than a car company. It's totally irrational that the company is valued higher than VW.
I heard it said that Tesla is not a car company. It's an energy company -- and I think that makes sense.
It makes the valuation even more insane if you see batteries as being Tesla's core value.
maybe not just batteries. maybe a bigger move into "clean" energy. a little but of battery here, some solar over there. something something space?