The very early Aero S4 based Plus 8's had a side screen storage box: it was discontinued quickly as, I understand, screens tended to rattle and also jam in the letterbox slot.
Our Roadster had a side screen storage slot in the rear rack, again it was not as useful as it appeared for just the same reasons.
On the Plus 8 I either leave the screens at home, or put behind the seats.


Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...