Can't agree more. When I had the 525i shed on roundabout if people tried cutting into my lane I'd just not move and just say to myself if you want to crash then I am game. Obviously in the EVO I'd rather not take the risk of them forcing their way in, but in the 525i I just held my ground.
Don't get me wrong if they put their indicator on, politely manevoured I will happily let someone in. But its the ones who seem to do it on purpose and its those when I was in the 525i or even the 306 I just hold my ground as I don't care if they crash into me, they are in the wrong.
Roundabouts you see it a lot people seem to use the whole roundabout not caring if they might cut you up or cause you to move out of their way, it was times like this where the 525i was very useful.