Most like BMW Styling 42.
If that is correct, they come in 1 piece and a nice (very nice) 2 piece in various sizes:
http://www.bmwstylewheels.com/bmw/42
The size information is not accurate, i have seen some in 16", 17x8, 17x8,5 as well as 18" sizes. I guess it depends on the market/region.