Oh yeah forgot to mention they're CVR12s, I'd like about 2ft^3 per sub, and like I said I prefer vented, but I forget the spex for sealed (I think its 1-4.5?). I like deep bass, not closer to the mid range, so the more air space the better.
I may mess around with some box design progs - I'm just not sure how to build a box that's sure to fit. Yeah, I could measure the openings of the trunk (or maybe even the entry from inside the car, and determine dimensions like that but it's kind of hard to do when the trunk opening is designed like it is.