So it may not be as cut and dried as everyone thinks; car seats (over age 2) may not actually make any difference. Good luck finding a politician who is _against_ car seat and booster seat legislation, though; that would be political suicide. Proving once again that government often doesn’t work in our best interests? (There have been other examples of dumb gov’t safety laws recently, based on zero _real_ deaths or injuries; I’ll see if I can dig some of them out of my memory).
The Seat-Belt Solution – New York Times
bq. Perhaps the single most compelling statistic about car seats in the NHTSA manual was this one: ”They are 54 percent effective in reducing deaths for children ages 1 to 4 in passenger cars.”
bq. But 54 percent effective compared with what? The answer, it turns out, is this: Compared with a child’s riding completely unrestrained. There is another mode of restraint, meanwhile, that doesn’t cost $200 or require a four-day course to master: seat belts.
bq. Even a quick look at the FARS data reveals a striking result: among children 2 and older, the death rate is no lower for those traveling in any kind of car seat than for those wearing seat belts. There are many reasons, of course, that this raw data might be misleading. Perhaps kids in car seats are, on average, in worse wrecks. Or maybe their parents drive smaller cars, which might provide less protection.
bq. But no matter what you control for in the FARS data, the results don’t change. In recent crashes and old ones, in big vehicles and small, in one-car crashes and multiple-vehicle crashes, there is no evidence that car seats do a better job than seat belts in saving the lives of children older than 2. (In certain kinds of crashes — rear-enders, for instance — car seats actually perform worse.) The real answer to why child auto fatalities have been falling seems to be that more and more children are restrained in some way. Many of them happen to be restrained in car seats, since that is what the government mandates, but if the government instead mandated proper seat-belt use for children, they would likely do just as well / without the layers of expense, regulation and anxiety associated with car seats.
Followup material can be found at “Freakonomics”:http://freakonomics.com/times0710.php
Jeff K 
Harald Koch 
Mike Hickman 
Darren Campbell
I love this story. :-)