Vehicular Ad hoc NETworks (VANETs) have attracted much attention in the last decade. Many routing protocols have been proposed for VANETs and their performance is usually evaluated and compared using simulation-based studies. However, conducting reliable simulation studies is not a trivial task since many simulation parameters must be configured correctly. The selected parameters configuration can considerably affect the simulation results. This paper presents a methodology for conducting reliable simulations of routing protocols in VANETs urban scenarios. The proposed methodology includes relevant simulation aspects such as measurement period, selection of source–destination pairs for the communication traffic flows, number of simulations, mobility models based on road city maps, performance metrics and different analyses to evaluate routing protocols under different conditions. The proposed methodology is validated by comparing the simulation results obtained for Ad Hoc On-Demand Distance Vector (AODV) routing protocol with and without using the proposed methodology. The obtained results confirm that by using the proposed methodology, we can achieve more reliable simulations of VANETs routing protocols.