if you'll notice the "crease" is in the lower third of your window and the window folds in the upper third. The "crease" is formed when the roof supports press on the plastic window when in the retracted position. Manual tops are less prone to crease since the top motor doesn't force the top down. Anything that displaces the pressure from the window will work. However I'd keep it to a minimum as you do not want to add pressure to the sides (seams) of the window where separation can occur. Towels are also a bit limiting as you have to get out of the car to retrieve them when putting the top up. We designed a rear window protection part that is very much like the BMW window blanket except it has an integrated high density foam core which helps to spread out the pressure from teh roof supports and minimize the "crease". It has two attachment straps that hook inside the roof so you can pull it in from your seat if you put the top up while seated and it will not blow away. if you want to know more e-mail me.