Well I couldn't find these wheels on Felgen Katalog (http://felgenkatalog.auto-treff.com/), unless it is a wheel that a picture hasn't been found for it yet.
I suspect perhaps that these are aftermarket rims? The centre cap is in very bad shape, different colour (different metal?) and banged up quite a bit. How on earth is that possible? Kerbing your wheels usually does it from the edge of the wheel, not the rim of it.
I believe with BMW wheels, the part number is stamped on every wheel, not just one.