Same problem with my 2012 328i: loud wind noise when doing > 50 mph.
NOT whistling, just copious amounts of wind noise, rather suitable for a $17k car. I drive a 2012 A4 in parallel and there is no wind noise.
But hey, this is the Ultimate Driving Machine, right? Not the Ultimate Luxury Machine. So be grateful you have a windshield in the first place
Or maybe there is a $6,500 optional package hidden in the ordering form that gives you the inimaginable luxury of not having tornados around your years.
Oh, how I love BMWs ...