Really depends on what it is... I guess you could use any upholstery cleaner on it. Just do a little spot out of eye sight to make sure it doesn't fade the cloth before doing the center of the seat. Some of the guys have been using a product with oxy.
Ditto.I would first try a carpet cleaner, try it in an inconspicuous location first to make sure it wont mess up the fabric, then go for it. If that doesn't do it you might have to have it steamed cleaned.I dropped a piece of sausage from my pizza during one of the very few times I have eaten in my car. Cleaner didn't work (only made it worse), professional steam clean worked for about two days then it was back again, now I am getting seat covers. That should do the trick. Good luck, stains on these seats seem to be hard to get rid of.