I dont see any problem with all the model designations. Remember, this is all a $ thing. The 2,4,6,x4,x6 will rake in the dough simply on the premise of charging more for people willing to pay for style. True they will have nicer interiors, more std sporting options, but there will be negligible difference in platform or R&D expense on bmw s part. Bmw will make a killing on these models, just like the other poster stated about the audi a5.
For those who place a priority on style, why not gouge them a little bit
2014 335i RWD: ZMM, ZDA, ZDH, ZPP, ZTP, 2NH, 2TB, 5DL; Z4A MPPK; AW ext / VB int
2014 ML350: P01, R33, 297, 319, 846, 864, 889, 996; LB ext / AB int