Sean Nemeth, the owner of a plug-in hybrid Chrysler Pacifica, was perplexed when earlier this year he received a rather surprising recall notice, advising him to park his vehicle outside and away from structures. The notice informed him that his particular model is at risk of catching fire—even while stationary and turned off—and the cause is still unknown. “What am I supposed to do with it then?” said Mr. Nemeth, recalling his reaction at the time. He eventually decided to park it across the street from his house in a low-traffic cul-de-sac. His predicament has become more commonplace in recent...