Get a bottle of Genesis 950.
Amerikal Store Shopping Cart
Water is the key to making it work. Don't think diluting it less makes it work even better. Mix as stated and I can damn near guarantee you any stain in your carpet will go away after using this stuff. Wet the area FIRST, then use a small brush and very lightly agitate the carpet while spraying the Genesis 950 on it, let it dry and vacuum it afterwards.
Sounds like your issue is the headliner. I would recommend covering the seats if they are leather. Not sure how this stuff would do on leather. It's strong, but not harsh to use at all.