I think my head is empty, there is this constant whistling sound.
The Ferrari F12 has an external duct that bleeds air away from the A-pillar and routes it around the rear view mirror.
They call it an aerobridge.
www.car-revs-daily.com/2014/12/15/2014-mclaren-650s-gt3/ shows this rear view mirror without commentary:
Possibly an annular air curtain? Coanda would be proud.