Had this on my classic mini cooper. as mentioned before a wet dry vac will do the trick.
Wait until summer and remove the seats from the car to dry. When dry apply some of this as it will protect from further stains
http://www.waxamomo.co.uk/index.php?app=ecom&ns=prodshow&ref=cgfgp
I'm lucky as my mum does cleaning for the council and she borrowed one of these
http://www.argos.co.uk/static/Product/partNumber/4064822.htm?CMPID=GS001&_$ja=tsid:11527|cc:|prd:4064822|cat:kitchen+and+laundry+%2F+vacuum+cleaners+%2F+carpet+cleaners+%2F
not sure why above link didn't work try copy and paste ^^^^
It will come out as I have done this more than once on several cars.
Wait until summer and remove the seats from the car to dry. When dry apply some of this as it will protect from further stains
http://www.waxamomo.co.uk/index.php?app=ecom&ns=prodshow&ref=cgfgp
I'm lucky as my mum does cleaning for the council and she borrowed one of these
http://www.argos.co.uk/static/Product/partNumber/4064822.htm?CMPID=GS001&_$ja=tsid:11527|cc:|prd:4064822|cat:kitchen+and+laundry+%2F+vacuum+cleaners+%2F+carpet+cleaners+%2F
not sure why above link didn't work try copy and paste ^^^^
It will come out as I have done this more than once on several cars.