When will the Tesla bubble burst?

How much would you pay to park a shiny new Tesla on the driveway? Perhaps fifty thousand pounds? Or seventy thousand? If you were looking at a top-of-the range Model X, which retails in the UK at £81,000, but allows you to look down smugly on all the gas-guzzling SUVs also clogging up the streets of Chelsea, perhaps ninety or a hundred thousand? 

Well, here is an odd fact: the stock market is valuing each of those cars at more than a million dollars (£750,000).