I think I can add something to this!
It's my understanding that the interior warranty is just a warranty against premature wear/stains etc. I don't think BMW applies any products to the interior. If they do odds are it's something like a cloth and vinyl scotch guard (which I suggest everyone does anyway, its good stuff!). Don't use the carpet stuff on leather though (just in case someone was about to), leather has a porous vinyl on it and the carpet stuff will close the pores. Scotch guard makes a product specifically for automotive leather.