Today's advanced simulators facilitate thorough studies on vehicular ad hoc networks (VANETs). However, the choice of the physical layer and the mobility models in such simulators is a crucial issue that greatly impacts the results. Realistic simulation of routing protocols in VANETs is still an open question. Indeed, only a few works address routing protocols comparison performed under realistic conditions. This paper compares common reactive, proactive, hybrid, and geographic routing protocols using a simulation platform integrating a realistic physical layer and mobility models. It also presents and analyzes several reactive protocol enhancement propositions dedicated to the VANETs context, such as multipath routing, but also protocols tuning, which allows it to adapt faster. They all have lot of attention and are typically proposed to increase the reliability of data transmission. This paper studies the behavior of each protocol in different situations and analyzed their advantages and drawbacks. Results presented in this paper give an important explanation on the contradictory results found in similar works. Finally, our realistic simulations show that reactive protocols are the best suited for VANETs, and more especially the dynamic Mobile Adhoc NETwork on-demand protocol.