Vehicular communication intends to improve the traffic safety for decreasing number of accidents and manages traffic for saving money and time. In vehicular communication, vehicles communicate wirelessly and so security of this network against attackers should be considered. To become a real technology that has public safety on the roads, vehicular ad hoc network (VANET) needs appropriate security architecture. Secure architecture should protect it from different types of security attacks and preserve privacy for drivers. One of these attacks against ad-hoc networks is Sybil attack that attacker is creating multiple identities that are identities belonging to other vehicles or dummy identities made by the attacker. Attacker is using them to gain a disproportionately large influence in the network leading to accidents or causing delay in some services for the driver using only one physical device. In this paper we present a case study of different selective methods for Sybil attack detection in vehicular networks and discuss about advantages and disadvantages of them for real implementation.