i know that, you know that, the brother knows that, but the design has a flaw and it could be blamed, a freshmen law student can get the win easily. Besides you know car manufacturer almost never win against law suit, in fact they usually settle outside of court which is still a loss.
You keep saying it is a design flaw but is not. BMW specifically notes this feature of the car in the manual. Design flaws are not explained out by manufacturers in the owners manual. The car was designed to work the way it did, for whatever reason.
In addition, before the owner's manual is released to the public a team of lawyers vet every page to ensure there is no liability on BMW's part. This will not be an "easy win for a freshman law student". BMW showed due diligence in notifying the public about the features of the car.
It is akin to those people that sue cigarette manufacturers when they get cancer from using cigarettes, despite the fact that the Surgeon General's Warning has been on every pack of cigarettes sold since 1966 (in the US).
Still, BMW will probably settle this out of court.