Rubber treatment products will make the mat look better, but I don't find any proof of the claims that they make rubber last longer. That said, I use Griot's Garage Vinyl and Rubber Treartment. It leaves a very natural looking finish - looks ilke new, untreated rubber.
Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex