Call me sentimental, but while everyone was lauding Tesla Inc.’s astonishing rise to a more than $1 trillion market value on Monday, all I could think about was how wretched the rest of the auto industry must feel, and how they might respond.

In just one frenetic trading session, Tesla added $118 billion to its worth, or almost double that of Ford Motor Co.’s entire market capitalization.

The trigger for this latest surge — a deal to supply 100,000 Teslas to Hertz Global Holdings Inc. — is a head-scratcher, as it represents "only” about $4.2 billion of revenue. And arguably it’s not even this year’s most significant car rental deal.