A good external cue to which tranny is in use is to check if it has rear disc brakes. Simultaneous upgrade yung 5AT and ventilated rear discs on the 2012.
On the inside naman it should have paddle shifters and a chrome accent on the dials. Here's a graphic from Mitsubishi on what changed with the 2012 model:
Source: Mitsubishi gives more reasons to enjoy the ride with the 2 12 Mitsubishi Montero Sport - Mitsubishi Motors Philippines Corporation
2011 Year Model 4 speed pa lang kasi 4 speed lang amin. Unless they refreshed it during the tail end of the year for the particular unit your are specifically looking at.
2012 yung nagkaruon na ng paddle shifters sa steering wheel column for the GLSV, dati manual mode sa AT Shifter lang.