Remove Tesla’s non-repeatable profits, and the stock has never been more expensive—now boasting a ‘core’ PE of 632

Somehow, Elon Musk managed to garner pretty good notices from both Tesla’s performance in Q4, unveiled after the market close on January 28, and the vision he detailed in the earnings call that followed. Wall Street analysts generally applauded the numbers as “a beat,” and investors didn’t seem overly disappointed, pushing shares just slightly lower at the open the following day.

Musk’s a bit like a playwright allowed to author a flop, then write the reviews—reviews so glowing that they...