The chance of finding this answer is slim, but here it goes. Has anybody with a wagon checked the volume of the sub enclosure to find out its volume? Is it even an actual enclosure?

I've been thinking of getting a thin 12" sub that needs .4-.6 ft^3, and I'm thinking I could just make a fiberglass pod in the factory location or use whatever is there. Anybody know?

 

I don't have a wagon but i would assume it's probably the same free - air woofer from the sedan?
You could probably put your own enclosure in the factory location.

 

I'm assuming that you're probably right. Obviously the back wave is decently sealed off, so I have wondered if it is actually in an enclosure. Anyways, I went ahead and pre-ordered the sub: Stereo Integrity BM mkIV: 12", 3.2" mounting depth, 0.5-0.6ft^3. This might be a slippery slope of audio upgrades. Actually, I ordered 2 to maybe redo the stereo in my other car.

http://stereointegrity.com/index.php?id=47