i understand exactly how you feel about the quality of the parts
along the years this is pretty much my opinion on bmw parts: the ones that i had to replace most of the time they looked like they were designed not to last really, or so cheap made that its ridiculous. cooling system is a weak spot, lots of common water pump failure (premature) most due to "quality" of the plastic prop, expansion tank failure again must be quality of plastic, i mean i understand it's hot and all where it's located and etc. but there should last longer. considering how many problems e36 M3s for example had with stupid design and quality of cooling system in those cars, you'd think bmw would make it more of a priority, well even today look at the new 335i, whats first issue with that car? running too hot, that's while brand new what about down the road? lol