2008 BMW X3 with 59,000 miles sheared all 4 motor mount bolts in normal street driving.
BMW said tough luck.
A quick internet search indicated this was not an isolated incident, many other relatively low mileage BMWs have had sheared motor mount bolts.
I believe this problem to be a serious safety issue and filed a complaint with the National Highway Traffic Safety Administration.
I encourage others that have had similar problems to file NHTSA complaints at the following website:
Click the REPORT A VEHICLE OR CHILD SEAT DEFECT Tab and submit your complaint.
If there are enough complaints, BMW will, hopefully, be forced to acknowledge this problem.