Attachment Parts On Upper Side Of Rear Spoiler Lower Section:

Stick on felt strips (1 and 2) on left/right.

1. 430 mm long
2. 100 mm long

Installation: 

Adjust spray nozzle for rear window wiper.

Fig 1: Sticking On Felt Strips (1 And 2) On Left/Right

Courtesy of BMW OF NORTH AMERICA, INC.