Didn't know this thing even existed.
https://skyermotorsport.com/products/bmw-z4-e85-roadster-top-side-covers
Googled about it and found this. Honestly I would spend money on those covers.
Car looks great with them.
EDIT: just read that you have to remove them when you want to put the roof up... That sucks since I almost always put the roof up when I park the car. Now I'm thinking if it's worth spending money on those.