I've searched any concrete answers about this to no avail. The dealer did some engine work for me ( gaskets etc) and drove my 2012 X6 for 100 miles without the stiffening plate. As everybody knows it says " Do not drive without the stiffening plate" The plate was laying in the trunk with the bolts in the box. All the BMW manuals say " Driving without the stiffening plate is PROHIBITED" I have all of this documented with pictures and witnesses just in case there would be any damage. Please share any knowledge about it. If you are by any chance a BMW rep you are welcome to contact me thru the PM system.