Whether or not they want to build their own cars, I don't know, but what the hiring indicates is that they want to have and develop skills and knowledge in dealing with self-driving cars (i.e. the future). It would make short-term financial sense for them to buy self-driving cars from other manufacturers and then Uberfy the interface, but the caveat is that they will be giving this key supplier a lot of negotiating power, which could be detrimental to their long-term business. If instead they partner with an established car manufacturer to create an Uber line of self-driving cars, the balance of power is more equal. In both cases, they need to be a master of this technology, and they need to develop this expertise now, and not when the future becomes the present.