The factory floor mats in my '18 looked clean until I pulled them and compared to the carpet underneath. There were Maple tree seeds and dirt gathering around the edges. Smark's recent comments on "proper" mats sent me shopping. At $63 delivered, OMAC floor liners seemed worth a try.
The company rolled the package tightly and stuffed it into a 4x8 inch box, so I laid them out for 24 hours to flatten. First impression was that they didn't have the nasty smell that most rubber mats have. I assume that's because they are made of thinner black plastic... much like kiddie wader boots or rubber overshoes (for you older readers).
The driver's side had mounting notches, but the left one is misplaced and no cut-out in the passenger side. (Maybe because these are listed for pre-18 cars? EU cars? Or just a screw up.) The right hole was in the proper place.
driver mat 2.jpg
After warming the car a couple times they formed themselves to foot well shape very nicely. The thin rubber will allow me to install the factory mats over them, if I choose. This photo is right after install before the rubber relaxed against the sides of the foot well.
The passenger side doesn't have a retaining slot cut in it. I could cut slots, but will probably leave them as-is. They don't move around.
In the rear the mats fit perfectly, extending well under the seats. On both sides they extend to the floor bracing. On my car I'll have to trim the passenger side because the amp is installed there... or probably just leave it out since that area is for storage.