I think it doesn't fit. I have both cars, an ICE with the Sony sub and an FFE.
On the ICE, the sub actually goes in a space to the right side of the rear hatch area (taken up by battery on the FFE). The amp, and wiring are all under the floor panel with the spare tire (also taken up by the battery in the FFE). The wires might still be there, as I think the wiring harness is similar between all cars (the non-sub Sony ICE Focus have the wires).
Not certain about the wires though.
You're probably better off getting an aftermarket sub.
Depending on the sound system you have, you might consider upgrading the speakers before getting a sub. I've had three FFE's, two 2012 and one 2013. There are two versions of sound - crappy and good. And crappy doesn't go with production date or year. I think Ford was just pulling random speakers from the parts bin as they built these cars. Some were Sony, some were some generic junk. Guess what I'm saying, they didn't start using good Sony (or somebody else's speakers) at some point in product. If that had happened, my three cars wouldn't have sounded so incredibly different.
