I was just recently talking with my brother and some friends about the exact same thing. We came up with the a similar solution: after 65, mandatory driver's test every 3-5 years to keep your license. It is truly rediculous to watch an elderly person drive who shouldn't be. 10 mph UNDER the speed limit, swirving like a drunk, etc., etc.. But hey, they are just harmless old people, right?? If I ever have any political power... that's how I'll use it.