The performance of protocols and architectures for upcoming vehicular networks is commonly investigated by means of computer simulations, due to the excessive cost and complexity of large-scale experiments. Dependable and reproducible simulations are thus paramount to a proper evaluation of vehicular networking solutions. Yet, we lack today a reference dataset of vehicular mobility scenarios that are realistic, publicly available, heterogeneous, and that can be used for networking simulations straightaway. In this paper, we contribute to the endeavor of developing such a reference dataset, and present original synthetic traces that are generated from high-resolution real-world traffic counts. They describe road traffic in quasi-stationary state on three highways near Madrid, Spain, for different time-spans of several working days. To assess the potential impact of the traces on networking studies, we carry out a comprehensive analysis of the vehicular network topology they yield. Our results highlight the significant variability of the vehicular connectivity over time and space, and its invariant correlation with the vehicular density. We also underpin the dramatic influence of the communication range on the network fragmentation, availability, and stability, in all of the scenarios we consider.