The thinners cut through all the grime to reveal clean vinyl. I think it removes a thin layer of vinyl (almost like T cutting paint) so go carefully. On checking the area where I had cleaned off the paint (a week or 2 ago) the vinyl is fine - no cracking or sticky) so give the seat a good clean with a nail brush, dryed it off then went over the entire seat with the rag soaked in thinners, as you rub the seat, the dirt and faded areas clean up well.
It was warm and sunny today so this probably helped to evaporate the thinners quickly - you need to have a good supply of rags as they get dirty and will smear the surface.
When this is done, I washed the seats again to remove any trace of thinners, dryed them and applyed some Autoglym vinyl care cleaner - the vinyl looks like new now
![Happy :D](./images/smilies/icon_biggrin.gif)
Try this at your own risk though - its probably quite a brutal way to clean seats
![Whatever :roll:](./images/smilies/icon_rolleyes.gif)
First photo is the seat half cleaned - light is not to good, area on left is the cleaned part excluding the centre ribbed area, second photo is the finished seat.
![Image](http://i143.photobucket.com/albums/r159/MantamadGTE/Morris%20Minor/seat.jpg)
![Image](http://i143.photobucket.com/albums/r159/MantamadGTE/Morris%20Minor/seat1.jpg)