Then they've just recently started breaking that out, as they used to only provide overall "good, fair, poor," etc. ratings and didn't separate anything.
Also, IIHS doesn't measure rollover damage. And side impact, especially below the beltline, is not mitigated by the structure above the beltline, so I'm not sure how the IIHS tests are relevant to this discussion.
FMVSS216 governs roof crush (i.e., rollover) protection and it continues to be revised upwards in terms of capacity. I haven't read the latest reg (they just upped it again) but prior to it, the requirement was for the vehicle to be able to withstand 1.5 times its own weight on its roof without collapsing. The last time I looked, the new spec was going to be 3 times its own weight. It's one reason why the Crown Vic will be exiting production, they just can't make that behemoth comply with the 3X rule without a complete redesign that no longer makes sense - and it already has some pretty hefty A, B and C pillars. Edit 2: You can, unfortunately, hide an entire CB650 in the blind spot generated by the B-pillars alone.
Edit: And while I'm at it:
Let's get away from the politics for a moment. Is this actually such a bad thing? I don't think it is. I think it's a good thing.
It's not expensive and doesn't compromise driving dynamics
This isn't the backwards motorcycle, which would have destroyed the dynamics of motorcycle riding. This isn't going to add $2,000 to the cost of each car, like others have said. It's more like mandatory LATCH tethers in the back seat. I'd be surprised if it added $100 to the cost of each car, and the weight is inconsequential, and it has no other effect on how the vehicle drives.
All you need is a two inch by three inch screen, a cheap ol' webcam, and a little electric turret like side mirrors use to adjust. That's it. On cars with a "vehicle information display" or some such thing, the screen is already in the car. It's cheap. It's light. It doesn't interfere with driving. Is that really so awful?
[citation needed] - please estimate cost for a 180/180 (remember, it's supposed to be fixed and not movable) camera and a large enough screen for older adults to make out useful information on it. That would be about a 7" or 8" screen, by the way.
Edit 3: And the camera has to be waterproof, weatherproof, UV shielded, 12VDC powered, and oh, yeah, have auto exposure. It will also have to work for at least 5-7 years (warranty) if not more, and in addition it will have to be night vision capable. So a cheap little webcam isn't going to work.
It actually does add safety
Somehow, in the past ten years or so, designers decided that visibility doesn't matter. Vehicles got higher, beltlines started to slope up from the front to the rear, and windows turned into gunslits. A vehicle that lets you see a four-year-old walking right behind your vehicle is now arguably the exception, not the rule.
Sure, you shouldn't drive down your driveway without knowing where YOUR kids are. But how about grocery store parking lots? School parking lots? You have to pick up your annoying brother at kindergarten. You strap him into the back seat, get in the car, and start backing up. If his friend comes running over to give him something, and runs behind your vehicle to get over to his door, are you going to see the kid? If you've got a modern 4x4 or a modern sporty car with an upswept window line and/or a big-ass wing, don't count on it.
Uh... you've NEVER been able to see what's behind and below your beltline in most SUVs. You couldn't in my Wagoneer, you can't in my Pathfinder. In fact, one of the "ran over my kid" lawsuits was someone here in Texas who ran over their (daughter?) with a Pathfinder, then sued Nissan because "it didn't have a camera".
You also couldn't see out the back with many of the large wagons of yesteryear, if you had passengers. And the Chrysler minivans weren't any better.
But only recently does it seem to be a problem....
There are other benefits
This little screen is not going to be black whenever you're not reversing. Manufacturers inevitably will tie it to the stereo. Now, when you plug your mp3 player in, you'll actually have a screen to scroll through tracklists and playlists on.
So now you'll be stuck with whatever crap and unreliable unit they put in instead of being able to easily swap it out for a much better aftermarket unit, or add more features later by the same means. Brilliant! I have this problem NOW with the XJR, and you want everyone else to have to deal with it, great!