OK, I’ll admit it: On more than one occasion, I have put my beloved Toyota Prius into reverse and come uncomfortably close to running over a few bystanders. It wasn’t because I didn’t see them (I swear!) it’s because they didn’t see -- or, to be more precise, hear -- me. While operating on its electric battery, my car is silent as a shooting star, so the pedestrians waltzed right into my line of fire, having no audible warning that I was approaching.