Try Vanish carpet and upholstery cleaner, using the foam (as per instructions) to gently "wash" the fabric. I've found this very good in the past and it leaves a nice fresh smell in the car.
I find "Neutrodol" very effective. It's a small sachet with gel inside that slowly releases an odour destroyer over a period of a month or so. It's available in most supermarkets for about €3.50. Also it helps to give the car a regular vacuum to remove stray bits of ash.