Audi headliner material..........gray

[Dave Conner]

 Since I am in
desperate need to resolve saggy headliner syndrome in my car before it
gets much worse ...

Mike,
Have you tried thumbtacks?  
Place a row of them about 4 inches apart across the headliner at the front
edge of the raised portion of the roof... just behind the sunroof area.
This will hold the material up and remove most of the slack, so no more
sag.  The weight of sagging material is what makes it worsen.  I did this
about 2-3 years ago w/ one of my cars and it's still OK.  You can't see the
tacks at all from the front seat because of the way the roof curves.  You
really can't see them unless you sit in the back seat and look up.

Dave C.