Nordic-Kat : You are absolutely great . I am happy to get to know you . Thanks a lot regarding the info on cleaning the leather . First of all I am absolutely loving my new 328i cabrio. Yes I know my engine is not turbo but the silky inline 3 liter 6 is smooth and pulls when needed plus I can always go a reverse with paddle shifters if needed for a highway pass or ...
As for The stains are not sticky , they are White hollow circles on the surface close to the back rests. I think they are water stains that stayed there for long and now combined with dust and penetrated to lower layers.I could not completely get rid of them by moist towel. I will try the leather cleaner that you mentioned and let you know how it works.
Kat : what's your BMW?