Use of wireless technologies is becoming pervasive in everyday life. Recently, research began analyzing their use on board of vehicles for several kinds of applications, ranging from traffic safety to fleet management and cooperative work, to entertainment and Internet browsing. In this work, we focus on safety applications and in particular on the approach proposed in the framework of the PATH project [1] for reliable diffusion of warnings to advertise problems in vehicular traffic. The approach in [1] is based on static parameters describing the environment. Unfortunately, in real environments those parameters may dynamically change over time. In this work we present performance measurements obtained by varying the parameters, to evaluate how the performance of the approach depends on environmental conditions.