IEEE 802.11p is a technology used for communication among vehicles, related to security issues, warning of incidents, or mere exchange of different types of information. Future cars will have the ability to communicate among them and with roadside data systems to spread information about congestion, road conditions, and accidents. They will also have access to travel-related Internet services, publicity from business nearby, tourist information, or even to exchange user files. In this chapter, the authors base their work on an ad-hoc highly configurable agent-based simulator that models communication among cars in a distributed vehicular urban network. Using this model, they provide different measurements concerning coverage and dissemination times to describe the behavior of the standard protocol for disseminating warning messages. Based on the results obtained, the chapter presents proposals to enhance the behavior of the protocol, some of them changing the specification, and others with the use of location-based information.