Visual updates for 2012 affect the 128i more than the 135i. The 128i carries revised circular fog lamps, replacing last year's horizontal lamps. Outboard of the fog lights, vertical slats improve air flow around the fenders, enhancing the car's aerodynamics. The headlights have new whitecaps up top, mirroring the headlight treatment across most other BMWs. These lights include a string of LEDs embedded in the caps; it's a visual cue used in the automaker's redesigned 6 Series.

On the 128i, an optional M Sport Package adds dark window frames and a more aggressive front bumper with three large air inlets. Rather than the 3 Series convertible's folding metal hardtop, the 128i convertible has a fabric soft-top that can open or close in 22 seconds, BMW says. It operates at speeds up to 25 mph.

The 1 Series remains a small car overall, about 2 inches shorter and narrower than a Scion tC. The BMW 3 Series coupe is about 10 inches longer.