I'm glad this topic came up...it allows me to
gripe about one of my major pet peeves with the e53. Why did BMW walk away from an ingenious cargo cover design that peaked with the e39 Touring?
The e34 Touring had the parcel net option installed in the top of the rear seats that allowed for 2 locations in the headliner (seat backs upright or seat backs folded down)...and the cargo liner "cartridge" is like the e53's...it can be pulled out of the cartridge for
privacy or rolled back for use...or removed totally from the vehicle.
e34 Touring cargo liner (parcel net is incorporated into top of rear seats)

The e39 Touring combined both the parcel net & cargo cover into the removable "cartridge"...still maintaining the 2 locations (fore/aft) in the headliner for the parcel net...but here's the ingenious part...
BMW installed 2 holders on the front of the bottom rear seat so that the cartridge can be stored inside the car.
The cartridge holders allows you to store the cargo liner (or use the parcel net in the "aft" location just behind the front seats) if you're out-and-about and come across something that you need to load up. If the item(s) take up enough space that you need to remove the cargo liner...you don't have to worry about where you're gonna put it if there's very little room left...it can be slid into the holders on the front of the rear seats:
(you can see the 2 cartridge holders attached to the bottom of the rear seat cushion in pic below)

(e39 Touring cargo liner & parcel net combined together along with storage holders)

(cargo liner stored in holders with parcel net in use in the aft position right behind the front seats)

(e39 cargo liner/parcel net in normal location)
The above worked so well on the e39 Touring which was built during the same time frame (1999-2003)...why did BMW remove the parcel net & eliminate the interior storage holders for the cargo liner cartridge? Why make the parcel net another cumbersome accessory that's in a extra bag that takes up more space if you want to keep it handy inside the vehicle?
Okay... rant/off