My GLK has a light beige headliner, How to clean this headliner? Any suggestions?

 

dilute some all purpose cleaner and wipe down

 

with warm water ... use a terri cloth.

 

If there is a mark or stain remember do not wipe, you should blot the fabric so as not to transfer the mark or stain to another area.

Whatever you try to use as a solvent you should look for an inconspicuous place and try the solvent first to make sure that it does not change the coloration of the head liner.

 

Pure naphtha works great for removing pen, marker, grease etc.