For 2012, 28i and 35i are the same. The only difference I noticed is that for the 28i the the surround of the rod on the bumper is black while on the 35i it is painted silver to match the rods. The 35i also has an exhaust on each side while the 28i has both tips on one side. Correct me if I'm wrong.
There is also an M-Sport Package available.
And the 35is has the M-Sport body but with the rods in the front bumper.