Most of us remember the numbers... TWA 800, JAL 123, United 93... major air disasters, resulting in mass casualties. However, as a favorite blogger of mine (usually on economics and politics) writes today, our road system takes many, many more lives. Roughly the equivalent of two fully-loaded 747's die every week on the roads in the U.S. The only difference is that they don't all happen at once, in a single, spectacular fireball, so the only place you're likely to hear about them on the news is in the traffic report.
This is probably the biggest immediate reason to end our auto-addicted transportation system.