Well - it is the law around here (WA state that is - and many other states for that matter) that cars must give at least 3 feet when passing a cyclist. I find it pretty amazing that you feel most cars give you enough space already. I would heartily support anyone's efforts to get the word out to the driving world that they need to give 3 feet as I am routinely passed with inches to spare. If I were taller.... some of those mirrors really stick out! I don't think that most motorists are aware that they are doing it and just how dangerous it is - I think they both don't know about the 3 foot law and just how wide their vehicle actually is. If spreading knowledge of the 3 foot law gets them at least thinking about leaving more space I'm all for it!