A sleek, gold car pulls up to a bustling corner market, and a middle-aged couple alights. A woman eases a suitcase into the same vehicle's spacious trunk. Later, a doodle and its master watch rocket videos in the front seat as the car eases around the neighborhood. That's the vision shown off by Tesla CEO Elon Musk last week during a presentation broadcast from a set at Warner Bros. Studio, outside of Los Angeles. Some 20 prototypes cruised the movie lot as a series of mocked-up images showed scenes of the idyllic tomorrow these sleek people-movers could usher us into.

Pedestrians will quickly learn how to game tomorrow's robocar-dominated traffic system, often bringing it to a halt, according to a model based--of course--on game theory. "From the point of view of a passenger in an automated car, it would be like driving down a street filled with unaccompanied five-year-old children,"writes Adam Millard-Ball today in theJournal of Planning Education and Research. Millard-Ball, who teaches environmental studies at the University of California at Santa Cruz, modeled what he calls crosswalk chicken, in which a brazen pedestrian crosses in front of oncoming cars, daring them to run him over. Of course, in today's world, such effrontery is dangerous because drivers may be inattentive, particularly when operating under the expectation that pedestrians will not act like total jerks. But in the right context, say that of a college town--where students can be at once inattentive, inebriated, and jerks--drivers "adjust to the unpredictability of pedestrians and modify their speed and behavior accordingly," Millard-Ball observes.