Last November, I strapped into the rear passenger seat of an all-electric, four-door sedan with BMW test driver and 24-hour racer Jens Klingmann behind the wheel. It was a cold day at BMW’s Performance Driving Center in Greer, SC, and beneath the five-point harnesses, roll cage, and heavily camouflaged body, Klingmann had an unexpected co-pilot: a tiny black box called the “Heart of Joy.”It was an odd name for an interesting suite of tech features powering my brief three-lap stint on the 1.7-mil...