To be fair, it’s in good company. The 2012 Audi A4, Lexus ES, and Lexus IS all fell into the poor category. Still, the C-Class has done well in what the IIHS calls the moderate overlap test. That’s more like crashing half the car into a wall as opposed to clipping a pole at 40mph which is what the new test is like.
The result from such crashes are likely to cause the wheel to be forced in to the cabin, causing extensive foot and leg injuries. For example, on the C-Class their test dummy’s right foot ended up wedged beneath the brake pedal as the front wheel got pushed back into the cabin. Ouch.
Of the cars they tested, the only ones to even net an “acceptable” rating were Acura’s TL, and Infinti’s G sedan. Volvo, unsurprisingly, managed a good rating. They’ve been doing this test with their cars since the 80s, so their S60 passed with flying colors. Acura’s TL also made it through the test satisfactorily.
On the plus side, automakers have been pretty quick to adapt whenever the IIHS and NHTSA create new tests. Mercedes isn’t likely to buck the trend in this case.