The interior is man-made and does not absorb like leather would. My method is probably not the best but it is good enough and not exotic or expensive. I am pro-active and don't wait until things look dirty. Its mostly a maintenance process. I use an all purpose cleaner (APC) called Simple Green. Just a few spritz on a microfiber towel then wipe it down. Do the seat including in the folds and seams followed up with a dry microfiber. When doing the dash if you see a lot of APC before wiping with dry towel then you're using too much. For weekly maintenance it doesn't take a lot. For the non smooth headliner I don't know how to clean or maintain it.