Vehicular Ad Hoc Network (VANET) is a sub class of mobile ad hoc networks. VANET provides wireless communication among vehicles and vehicle to road side equipments. The communication between vehicles is used for safety, comfort and for entertainment as well. The performance of communication depends on how better the routing takes place in the network. Routing of data depends on the routing protocols being used in network. In this study we investigated about different ad hoc routing protocols for VANET. The main aim of our study was to identify which ad hoc routing method has better performance in highly mobile environment of VANET. To measure the performance of routing protocols in VANET, we considered two different scenarios i.e. city and highway. Routing protocols were selected carefully after carrying out literature review. The selected protocols were then evaluated through simulation in terms of performance metrics i.e. throughput and packet drop. After simulation results, we used MATLAB to plot the graph to compare the results of selected routing protocols with each other. Moreover, we computed the sum of output from each scenario to clearly present the difference in results. From results, we observe that A-STAR shows better performance in form of high throughput and low packet drop as compare to AODV and GPSR in city environment, while GPSR shows better performance as compare to AODV in both highway and city environment of VANET. Based on the results of performance metrics in different environments of VANET, we realized that position based routing method of VANET outperformed the traditional ad hoc topology based routing. However, it is hard to provide any universal routing protocol that can deal with all the various environments of VANET. The selection of a single routing protocol is hard in VANET because the protocol performance depends on vehicle speed, driving environment etc. That may vary from one environment of network to another.