This subforum is focused on the X5M and X6M, which actually have totally different shape mirrors (we don't know if they use the same glass yet, as no-one has theirs delivered!)
I know from personal experience that EU (at least UK) vehicles have a cool ashpherical lens that US vehicles don't. However, we drive on the other side of the road so that wouldn't work...
I'd ask the same question over on the main forum and see if anyone with more experience of the X5 has a better idea....