Book excerpt: [ANGLÈS] There are unlimited opportunities for civilian car to car application for VANETs. The priority research field for Car Manufacturers as well as Governmental Transportation Authorities is the safe navigation. Applications that may be able to inform the neighbouring vehicles about weather, road condition, traffic jams, and accidents can save many lives and also optimize the resources for emergency, improve the respond time to emergency among others important applications. Some of these applications will require security information services to promote its use. One of the most important security information services for the application usability in VANETs will be the privacy, more explicitly 'Anonymity' in the sense if someone wants to collaborate notifying emergencies, traffic state, suspicious driver behaviour, necessarily he/she will require to send for instance his/her estimated position but without being tracked. Base in this fact, this Final Master Project tests the suitability of anonymity web mechanism called Crowds over routing protocols in vehicular Ad Hoc Networks. A Crowds variant that does not consider self-forwarding specially adapted for VANETs is implemented over AODV (a reactive topology routing protocol) and a GPSR variant (a well-known position-located routing protocol) that includes the use of a buffer and building aware condition to select its forwarding nodes. Simulation tests were done using NCTuns 6.0 for a single hop scenario to measure the accuracy of the formulas obtained for ideal cases of Crowds, and evaluate its performance in a real multi hop scenario focusing in the End Server attack. Finally, results and future works related to improve this simple and promissory anonymity mechanism over VANETs are provided.