Rubber Floor Mats very stubborn to clean. Suggestions?

[Mike777G]

This has been one part of my detailing regiment that I feel could improve. I simply can't get rubber floor mats clean. My process involves using a strong cleaner and agitating with a brush then a pressure wash. The texture of the rubber just seems impossible to clean. Any tips?

 

[OnTheSpotMobile]

I have good success using the same method with OPC or Carbrite Interioir/Exterior Cleaner Degreaser, which I find are a very similar product. I spray them with water, then with the cleaner, let them sit while I'm cleaning the wheels for example, then come back and brush the hell out of them with a fairly stiff brush with long bristles that get into the places they need to go. Some of them require brushing in 4 or 5 different directions to get into the cracks. The honey comb shaped ones are the most annoying! Finish by spraying clean with the pressure washer.