The vehicular ad hoc network (VANET) is an emerging wireless network that allows vehicles to communicate among themselves and with road-side infrastructure. The downside to easy access is that the network can allow eavesdroppers to estimate vehicle locations based on communication signal properties, such as signal strength. Therefore, the successful deployment of VANET infrastructure, such as the U.S. Department of Transportation’s Vehicle-Infrastructure-Integration project, cannot be realized without addressing these security and privacy challenges. Our research showed that VANET applications could allow vehicles to be continually tracked and that such location tracking of a target vehicle can compromise of privacy of the user in that vehicle. Based on observed properties of mobile nodes in VANET, such as the group navigation of vehicles and the uncertainty of vehicle movement when merging/changing lanes, we proposed defense mechanisms that can protect privacy of vehicle users. Our preliminary work was presented at the workshop on Embedded Security in Cars (ESCAR) 2005.