DCT in M cars are a "truer" manual than DCT in Z4's. M car trannies have a neutral position, for one thing. In the Z4, if you take your foot off the brake at a standstill, you will idle forward, hence, no neutral.
2006 525xi, Orient Blue Metallic, Beige leather, Dark Poplar trim, Premium Package, Cold Weather Package
2012 Z4 35i, ED 2/24/2012, Melbourne Red Metallic, Black Leather, Carbon Trim, 6MT, ///M Sport, CW, PP, PS, NAV, CA, LED Angel Eyes, red calipers, pedal covers, stubby antenna.