Vehicular Ad hoc Networks (VANETs) have been largely impacted by social characteristics and human behaviours with the wide use of service applications in VANETs. Thus, vehicular communications can be considered as a social network for auto-mobiles in which drivers can share data with other neighbours. In this context, a trusted data dissemination claims our high attention. Besides the traditional public key scheme, this paper explores security issues of date dissemination through associating drivers' social relationships with vehicles in order to construct a trusted vehicular social network. Furthermore, a compositional formal approach (Performance Evaluation Process Algebra, PEPA) is introduced for performance modelling of such a network due to its outstanding features.