Automotive connectivity standards promise to usher in new apps and services that utilize vehicle-to-vehicle communications, and mobile app trends point to the potential of direct device-to-device connections. The convergence of the two, made possible by new hardware, system software, and programming abstractions, promises to realize next-generation mobile ITS apps. The city-scale impact of such convergence can now be projected using new evaluation infrastructure that captures interactions between humans, vehicles, devices and networks.