I have the same problem when I have the 2 grandkids in the rear seat.
Even with the windows up it's too much wind for speeds in excess of 40 Kmph.
With my Z4, we had a small OEM windscreen between the 2 headrests which was very effective,
I don't know why some entrepeneurial type hasn't designed and produced a small windscreen to go between the 2 rear headrests for those occasions when we have 2 wee ones in the rear and can't use the standard 1er vert windscreen.
Hopefully someone in China is scanning this forum.
