This 135i indeed features M-sport package, yet the wheel arches are regular - just appearing wider in this particular pic (perhaps due color, lighting, angle of shot, ...).
PS: I've noticed one interesting detail. The cars with intercooler & twin pipes (135i) wear M-package exclusively in all spy pics available. That makes me believe 135i will be a special edition - coming exclusively with M-sport package only. A top end non-M sports model - like eg. E53 X5 4.8is was. So, kind a "135is".