You've seen them, even if you haven't been bold enough to ride in one. They cruise through Valley streets and neighborhoods — and recently, the highways — cameras a-whirring, empty and unnervingly silent. Sometimes they turn from the wrong lane, run into a pole or even get pulled over. Mostly, though, they roll around town ferrying passengers to and fro while the driver's seat sits unoccupied. Pulling up next to one at a stop light is to gaze into a singularity, a disturbing peek at a sterile and post-human existence. Kids might call them "magic cars," and we might call them creepy as hell, but they're probably not going away. Like WALL-E, they'll amble along our desiccated roadways long after civilization has ended.