How do I clean fabric car seats without leaving water rings?

Water rings form when a wet area dries and leaves dissolved dirt and cleaner concentrated at its edge. Vacuum first, use a fabric cleaner sparingly, agitate gently and extract or blot as much moisture as possible. Feather the cleaning out to a natural seam or across the whole panel instead of stopping in the middle, and dry the seat quickly with airflow. Over-wetting is the most common cause of rings.