I too have a 2012 Sport with the Gray seats. I do not know of a specific cleaner but getting VERY HOT water with a rag and rubbing it into the seats seems to get the stains out (for now). I know this because my dog, a a boxer mix, loves to drool on the seats, to my chagrin. Eventually, I'll probably buy leather seat covers: {http://www.ridgelineownersclub.com/forums/showthread.php?t=113369}.
If you are looking for actual cleaning products, Mother's or Meguiar's are typically really good products.