Abstract: Dynamically changing targeted advertising content is dispatched wirelessly in real time via a cellular network from a remote web portal to a plurality of vehicles, and ads are displayed on a digital display mounted in a rear window of the vehicles. Vehicles communicate wirelessly to the web portal their geographic location, and cameras are used to record the effect of the ads on viewers in following vehicles. Ads are changed based upon criteria established by advertisers, changing vehicle geographic locations, and changing conditions such as areas, times of day, traffic on roads, and profiles of viewers.