I have used the steam cleaner from Safeway (it's red, called Rug Doctor) and the cleaning solutions they recommend on 4 cars now including my 08 Mps with the same interior as yours.
It worked awesome. I actually just did my skyline on the weekend. Cost was $50 for 24 hours including the shampoo and anti foam (which you don't need as I left it out accidentally).
You can literally see the dirt and stains coming out of the seats and up the hose. This is a pic of the water afterwards - and this was a very clean car to start with!