SAN FRANCISCO—Dr. Terrance Earnhardt, youngest son of the late NASCAR legend Dale Earnhardt, died Friday when the light-rail Muni Metro train he was riding home from his oncology practice derailed, delivering one final embarrassment to the racing family. "It's a shame things had to come to this, but at least they finally have some closure and can stop worrying about him politely moving to the center of the vehicle so that other bus passengers have room to board," said longtime family friend Darrell Waltrip. "I know it tore Dale up inside, but after Terry confessed he didn't like competition or going fast and had a deep interest in alternative transportation solutions that reduced society's carbon footprint, they never spoke again. It was for the best." The Earnhardt family is planning a private mourning lap Wednesday and has posthumously named Terrance the driver of the number 37 Quaker State Oil Additives Chevrolet.