Pretty sure I figured out what the wheels are--MRR GT-7.
http://mrrwheels.com/gt7.html
Found it by doing a quick search on eBay:
http://www.ebay.com/itm/19-BMW-E92-E...ht_7099wt_1163
That link is for the 19" version, though 20" is what is on the car.