This paper presents the measurements and analytical results made over important characteristics of wireless signals propagation for vehicular ad-hoc networks in motorway environments, including Doppler Effect, free space signal propagation, and system operating margin. In this work, we employ IEEE 802.11b wireless cards for inter-vehicular communication to analyze large and small-scale propagation models. Our results show that the Doppler Effect does not affect transmission between communication partners at high speeds in small-scale models. Finally, we realize an experiment to validate the former results in the worst case scenario, when the transmitter and receiver are travelling in opposing directions on a straightaway. Results show that at least 8 packets can be relayed when the transmitter and receiver antennas are mounted on automobile dashboards.