Permacrud is the irremovable layer of filth ground into the carpeting and/or floorboards of a hooptie
. It is usually comprised of crumbs of food, trash, rust, dirt, mud, spilled beer, tobacco, weed, and various types of "mold". This is the layer below the beer cans, snack bags, and cigarette butts.
Permacrud is formed over a period of years, appearing as vehicle "matures" into a hooptie
. It takes years of neglect, regular intervals of pressure from passengers' footwear, and exposure to seasonal temperature changes for permacrud to form.
Once formed, permacrud cannot be removed without removing the carpeting and/or floorboards.