Yea I can say I've learned my biggest lessons from mistakes in driving. Simple solution, give your kid a big old ass car and let them wreck it. That will teach them to slow down. Sure as hell made me slow down. I've had my share of near misses, too. Only these things are really what made the impression on me to slow down.
Edit: So in short, this isn't a very good idea if you really want kids to learn. Some things just have to learned the hard way. I think many of us wouldn't be such good drivers if we hadn't had the chance to screw up some.