Everybody needs to calm down.
In my opinion this is a true and unintended leak. This is a pre production model beeing prepped for camoflage / transport by a special BMW factory workshop:
- The flat black parts are spacers where panels and foil will be stretched over to hide actual contours. Just look how the parts cross the rear reflectors. No production part would be designed like that.
- The fins on the diffusor also act as spacers for panels/foil
- No tips on the exhaust also hint prototype
It would be very interesting to have a date of the photo.