A few have done it, yes. Go look in the trunk under your decklid area but the rear seat relese handles. You'll an an 8" hole cut out. Premium sound Mondeos came with a small 8" free air sub.
So you wnat a how to, eh?!
Go to crutchfield or google and do some research. Free air (also known as "infinite baffle" subs are few to none. You can not jsut mount any normal sub in their and expect it to work. To avoid rattle etc, many of us mount it to a piece of plywood and then to the decklid. The holes are already in the decklid, just need a couple long enough bolts with large washers and nuts for them to mount it up.
Couple brands that make IB subs, Infinity and JL.
Be prepared to spend BIG BUCKS on an IB sub.. the infinty 10.1 Refrence sub is about 200 bucks. PLus the cost of an amp, wiring, etc, etc. If you can give up about an 8"X10" area in the trunk.. INifinty makes the "Basslink" amongst other companies. It's an all in one enclosure systme with a built in amp. They are good for your applcation becomes they have "tuned" bass.. not thumping bass. Thos range in price from $159 and up. If you need anymore help/info, feel freeto ask.
