After Tesla’s market capitalisation swept past that of Toyota, then the world’s most valuable carmaker, in the summer of 2020, devoted fans and incredulous sceptics deployed a new unit of measurement. As the electric-vehicle (EV) champion’s share price rose, its worth was couched in terms of the combined value of the next two, then five, then ten biggest carmakers. A year ago Tesla’s market value surpassed $1.2trn, more than most…