Lots of good stuff at this site if you haven't already seen them...
http://www.bmw.com/com/en/insights/e...videocast.html
There's a few vids of design features, such as the magnesium panels to save vehicle weight (but same stiffness as steel). As you may recall, we complained about those panels being 1-piece and costly to replace in the event of a fender-bender. They go on to explain the reason for that is magnesium cannot be welded like steel, so it is done as one piece using high pressure to mold.
On a lighter note, they also have a video on the Tobacco interior.