Replace it with carpet or put carpet over it...I didnt mine in black and it looks really good just takes a little time and a razor blade..so much easier to keep clean
Back when I worked at U-Haul, we would clean the rental trucks when they came in. First, wisk broom to get out the big chunks, blow out with the exhaust of a vacuum cleaner, spray black paint to make it look new again.
I hosed mine out a few weeks ago after most of a gallon jug of cleaning concentrate spilled on the floor. Water got under the mat and it took about two weeks with the mat pulled up and towels under it to dry out.