Motivated by the recent surge in vehicular ad-hoc network (VANET) research and the promise of high-impact applications such as safety, navigation and infotainment services, we consider the impact of mobility mis-modeling on the design and development of this class of distributed systems. Focusing on urban environments, we use a state-of-the-art car traffic simulator to extract some of the key connectivity metrics relevant for the design of a vehicle-to-vehicle traffic information system. We compare such metrics against those obtained from popular mobility models, such as the random waypoint model and the Manhattan mobility model. Our results reveal striking differences in the connectivity profile of the network, thus casting some doubt on the adequacy of simple mobility models for the development of future VANET protocols.