From the Teslamotorsclub.com and Reddit is the above gallery of a Tesla Model S with some weird stuff on it. The consensus seems to be that this is a testing vehicle for the Model X crossover with the roof mount  simulating a high center of gravity and additional weight and the tire sensors showing the handling. The Model x is built on the same platform as the Model S so that seems feasible.  The picture set  was taken near UC Santa Cruz.