  Modern vehicles are equipped with more and more sophisticated computer
modules, which need to periodically download files from the cloud, such as
security certificates, digital maps, system firmwares, etc. Collaborative
content distribution utilizes V2V communication to distribute large files
across the vehicular networks. It has the potential to significantly reduce the
cost of cellular-based communication such as 4G LTE. In this report, we have
conducted a simulation study to verify the feasibility of a hybrid cellular and
V2V collaborative content distribution network. In our simulation, a small
portion of the simulated vehicles download the file directly from the cloud via
cellular communication, while other vehicles receive the file via collaborative
V2V communications. Our simulation results show that, with only 1\% of vehicles
enabled with cellular communication, it takes less than 24 hours to distribute
a file to 90\% of the vehicles in a metropolitan area, and around 48 to 72
hours to distribute to 99\%. The results are very promising for many
delay-tolerant content distribution applications in vehicular networks.
