Popped down to see the old man in Devon last weekend. He's got a Polti Vaporetto 2400 steam cleaner (for use in the house). Having previously raved about it's abilities to me, I decided to give it a go on the cloth interior of my Golf as the previous owner had a dog and there were a few grubby marks that wouldn't come out with the usual fabric cleaners.
F*ck me - what an awesome bit of kit!
It's a semi-industrial unit and costs about £200 - £280. You just fill with tap water then leave it to boil up. The steam is delivered through a karcher-style trigger at pressure. A variety of tools come with it for different tasks. Using it couldn't be simpler - just give the soiled area a few seconds of blast with the steam, then wipe over with a clean cloth. Hey presto - the area is clean and almost dry immediately!
Did all the seats in the end, plus the headlining, plus some areas around the handbrake with ingrained dirt. It now looks as good as new. All this without using any chemicals. It is really quick too.
Obviously you have to be sensible around any switches/electrical stuff but other than that it's really good. So good in fact that I brought it home with me (promising to give it back (maybe), at some point).
Would be interested to know if anyone else uses these things. If you've never used one then you'll be amazed how good it is.
At £200 it's not cheap but IMO well worth the money.