AUTOS: Revving Up for the Wankel

In the headquarters of Detroit's automakers, executive desk tops and coffee tables have lately sprouted plastic models of a strange-looking engine, and in high-level conversations around them, knowing mentions are made of something called an epitrochoid. Visitors soon learn that the models are see-through likenesses of the Wankel rotary engine—and an epitrochoid, in case they did not know, is the bloated figure-eight shape that its rotor follows when moving. Both the baubles and the vocabulary are just two more signs that the long-discussed Wankel has finally shifted up from being Detroit's...