Those Wilko's ones look like they'll do the job on leather and for three quid you can throw them away when they're dirty, which they will with the roof down.
My problem is the dreaded Alcantara* seat panels, which both rub and are a bu//er to clean**. And, on mine, they're Ivory White.
(*Is this Japanese cloth an expensive extra because it looks cool? :idunno: ** Until you discover Waitrose baby wipes.)