Originally Posted by Robert
Interesting. Doesn't heat cycling reduces ductility in steel or increases brittleness? Wonder what's the trade off BMW engineer was willing to accept. Thank for the informative video. I learned quite a bit. However as any marketing video it only provides 1 sided story. Of course there is a tradeoff between weight and safety. In this case the tradeoff may be neglect-able for intended purpose but it must be minuscule, to the 10^-6 decimal point because when BMW is producing a million car a year. If not it means BMW produces one unsafe car a year :P
As far as the ductility issue, I believe that's an issue during the forming process, but they apply heat treatment after the part is is formed - don't you agree?
I think the trade off is between strength vs lightness during a side impact and transfer of impact energy to the rest of the frame. I'm really surprised that they would be looking for weight savings on a B pillar, particularly since there's no way to laterally (side impact) strengthen it.
BMW for all apparent fanaticism, hype and marketing for e-dynamics, bio-fuel efficiency and general "green-ness" tends to build a relatively heavy sports car. Compare a e89 Z4 (a car I really like) and a Porsche Boxster or Cayman, which are about the same volume. Comparing apples to apples - DCT vs PDK - and the BMW weighs about 500 lbs US more. Compare an e85/e86 and they were pretty close. The e89 convertible top weighs about 200, so were did BMW pick up the extra 300 lbs?