To my eye it looks like Space Gray, left out in the Florida sun for 5 years without a coat of wax. I thought only old GM cars developed a patina like that. I guess it makes sense for those who prefer pewter flatware over sterling or tin over aluminum. But it's not for me.
2011 X5 35D Sport, DSB / Oyster
2011 535ix M Sport, TiAg / Black