I admire your effort, but I am reminded of Diane on "Cheers." Some might see that as an insult, but I'm betting you'd take it as a compliment.
The tragic part is that drivers imagine themselves as cool renegades, cranking their tunes in their Boxes of Individuality. Your note would only confirm their self-image.
What we need are pop-cultural images that depict car drivers as aßholes. You know how in movies, the guy with the British accent is always a villain? That's what we need for cars. We need images of cyclists in films who are heroic rather than comic. A protagonist with a bike in a movie — like "I Love Huckabees" or "40-Year-Old Virgin" or "Rushmore" — is likely to represent a futile struggle. Unfortunately, movies are made in Hollywood, where the car is God. We need to counter that. We need to make a cool bike movie.
So, uh...get right on that, O.K.?