The 135i's interior design is fairly traditional, with more upright shapes than sweeping contours. Dual-zone climate controls sit below the center air vents and optional navigation system, with BMW's latest-generation iDrive knob controller ahead of the center console. The system can now read text messages aloud or stream songs off a paired BlackBerry smartphone.

BMW says the cabin controls boast "a more refined look and feel" for 2012, though the layout is hard to distinguish from 2011's. In contrast to the seat belts that motor forward for easier reach in the 3 Series coupe, the 1 Series' belts are fixed onto the B-pillars.

On 135i coupes, the two-position backseat folds in a standard 60/40 split. The convertible offers only a center pass-through. Vinyl seats are standard, with leather optional. The M Sport Package adds unique headliner materials, an M-branded steering wheel and shifter, and sport seats with more aggressive side bolstering.