We currently have an ongoing master thesis that looks into this topic – context-aware advertising with cars. There are several interesting examples that this concept could work: e.g. Taxis that show location based ads (you can hire your area where your ad is shown, see , ). We think it gets really interesting if there are many cars that form a in-town canvas you can paint on. On the way back we checked out the screen adverts (include in the public phones) Jörg Müller works on – even with a navigation feature.
Looking for some more on the topic I realized that Google Patent search works quite well by now: http://www.google.de/patents
 Vert, Inc. http://www.vert.net/patented.html
 Hacking Taxi Cab Billboards. http://www.theshiftedlibrarian.com/2002/07/31.html#a2715