For my idea i would like to create bumper stickers that say something like:
if you can read this you're too close!
(that will be in small letters, so only the people who are actually too close can read it.)
A safe distance is always a car length behind.
That way not only does the driver reading the bumper sticker know that he is too close he also now knows the safe distance to drive and/or drive behind another car in order to help prevent bumper to bumper accidents, that can be easily prevented.
My friend is my inspiration for this idea. She recently was sitting at a stop light and she was waiting for the light to turn green when all of a sudden she felt a jolt. She turned around and saw that someone, who had been sitting too close behind her for a few minutes now, jumped the gun when the light turned green and started to drive, thinking that my friend was going to start moving forward as well. It so happens that this person was to close and even though my friend was about to move there was not enough room between them to allow the car behind her to start moving. She rear ended my friend.
With the bumper stickers I can pass them out to classmates and they will put them on their cars and they in turn will be aware of the rule as well as others on the road.