What is the best way to clean the headliner (ceiling) in an Audi A4?

I recently purchased a newer Audi A4, but the headliner (ceiling) is starting to look a bit dirty. What is the most effective method for cleaning the headliner without causing any damage?

The best way to clean the headliner in an Audi A4 is to use a mild cleaner and a soft-bristled brush. Make sure to test the cleaner on a small, inconspicuous area first to ensure it does not cause any discoloration. Use gentle, circular motions to clean the headliner and avoid using too much water, as it can seep into the fabric and cause damage.