Look into Gummi Pfledge. I don't know if that would help extend the life of the cover.
2001 530i/5 (E39), Topaz Blue/Stone Green/Black (118k miles) *very rare interior/exterior color combo*
2005 545i/SMG (E60), ED Order, Titanium Grey/Grey (lease over)
2014 535d (F10), ED Order Summer 2014: THIS IS THE PLAN SO FAR