Originally Posted by hlmiii
I've never heard a definitive answer. Again - it's probably the slightly different chassis/wheelbase and less rear overhang. In high-stress situations everything matters.
There is a longer distance between A pillar and B pillar support in the coupe. The vertical support is more evenly positioned and anchored in the sedan. That should also have some effect.
If your talking about whether the coupe or sedan is more rigid in regular trim...It is the sedan. I visited BMWNA and talked to some very knowledgeable people and although the difference is slight, there is a difference.