I think AA foam would do a good job too... the only problem with it (my concern) is that it will make the mats slick, which isn't a good attribute for floormats. It's a large reason why I only wash my rubber floormats. Yea, they don't look nice at all anymore, but I don't know what to do to them - it seems any type of dressing product would make them slippery.
Cleaning them... usually APC does the trick, but before that I just used some dishwashing liquid, palmolive to be specific. spray down the mats, pour a bit of liquid on, spread/"scrub" with an old body brush, then spray off again.
I did find that what detergent you use makes a difference. Palmolive did a decent job, but there's other liquid I have... "joy" something. It sucks for cleaning floormats, I might as well be using car shampoo to try to wash it.