It's 209 miles from the parking lot of a Chili's in Barstow, California, where we are, to the parking lot of a Carl's Jr. in Kingman, Arizona, where we need to go. I'm in a rented Tesla Model S, a sleek, battery-powered electric vehicle, with a travel companion. We're just about fully charged, and the car estimates it can travel 247 miles before we need more juice. That's a buffer of 38 miles, which should be more than enough to reach Kingman. We'll soon realize it isn't.