Premium in the new (2014) Forester 2.0T is only recommended, not required.
Any current production turbo vehicle from any manufacturer can easily be made to run any grade of fuel*. All engines have knock sensors, and these will change the engine parameters so that they'll run 87 RON fuel fine, even if the manufacturer recommends premium, albeit at some lower performance level. In our car (see sig), we've never run anything but 89 RON midgrade (have drive it 115K so far, 137K total, everything is running fine), although the manual recommends 93 RON gas. Neither of us can tell the difference in performance.
*It is true that not all vehicle are set up to do this; some manufacturers set up engines to perform so that running grades of fuel other than premium is a no-no, but these will state "premium required."
