[jadnashuanh]

The problem could have been inconsistent quality from a vendor (BMW is almost uncertainly not the maker of the bolts), an out of tolerance or inconsistent tool that torqued things (those things get checked periodically, but if it is inconsistent, it may take awhile to show), or probably several other issues. BMW sample tests vendor parts, and picks a certain number of cars off the production line for more extensive testing to verify things are okay. They also run EACH vehicle on a dyno at up to 100mph to look for issues (far faster than people in the USA should be driving, anyways!) while monitoring lots of things to look for any issues.

If you ever get a chance to tour one of their factories, you'll find a huge amount of the work is done either by robots or assisted by humans with power tools - this leads to very good consistency in product. You can monitor and qualify a vendor, but they normally only get recertified after awhile, and that is why they do sample testing. You want someone to check each part as it goes into the vehicle, buy something like a Rolls, and that's no guarantee it may not have a recall once in awhile, too.

I worked in the defense industry, and on some jobs, we obviously used microprocessors but we had a requirement that they must operate at far higher temperatures than a typical consumer situation. There's a reason why what you could buy for maybe $100 cost the military $400 - you had to buy and test them and then either throw away maybe as many as 3 out of four because they failed before you found one that worked the way you wanted. For non-critical situations, you'd just buy one off the shelf, but that isn't always a viable option. This is rarely the case with cars...things are only as good as the parts that go in, and everyone is wanting more for less - you set your standards and go from there, fixing issues when something goes wrong.

A news article that came out recently ranked the timeliness of recalls, and BMW sat on top - not in the quantity of recalls, but their timeliness. It did not distinguish between mandatory and voluntary, which would have been interesting.