IF we are talking about the three piece shroud (plus foam rubber strip on top) that guides all the water from the windshield base away from the testy bits:
The original parts were prone to cracking from heat cycles. BMW revised the fiber content in these parts a couple years ago, they are supposed to last longer now.
Ppl complain about them being pricey, I didn't think they were too bad (using CCA discount), as they are kind of important. I got new ones last summer and installed all. Very pleased.

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2012 e70 X5 50i MSport "The Boss" black on black *Well Optioned*