I've always suspected that it's dangerous to ride with a severely reclined seat (say, a 150-degree angle), as many people do when they're sleeping. I'd agree that in that extreme, the concept is pretty intuitive.

But what if the seat is reclined only a small amount? Does that pose a significant risk? If so, what is the optimal angle? 90 degrees?

If only a small recline poses real risk, then I don't think a call for greater awareness is misplaced at all. The layperson can't really predict the physics of a car crash; if the fit of the belt feels normal, how else would one know?

I don't think the belt ever feels normal, except that you get used to whatever you normal do.... if you typically wear the belt across your belly, that will feel normal to you, even though it's a bad idea (you can do serious damage to the organs in your abdominal cavity that way.)

The answer is: sit up straight. The top portion of belt should be against your shoulder and rib cage and the lower portion should be against your pelvis. The fit should be snug. If you feel slack - an inch or more - readjust the belt and/or your position.

Personally, I think there should be more emphasis on proper seat belt use, but people hate the idea that driving is dangerous. To most Americans that have never been involved in a serious crash, driving = freedom Still, a question or two about it on the driver's test would be worthwhile.