Car subwoofers for home sub use: Whynot? why?

I plan on using some car subwoofers for a home sub.
What is the reason not to?
The 4 ohm is no problem...
So what else is wrong with this picture?
I plan on sticking (2) 8" Polk Momo subs into a box from a dead Klipsch (hunk of crap) computer sub.
8" pair and use the still functioning Klipsch sub 9the other channels are dead)
I have a Infinity 12" home sub that I want to put a 12" Infinity Perfect 12 into.
Why not?
OR: a Polk Momo 15" sub in a custom box.
(the Momo are a physical match for the Canton speakers I have)
And I have Carver ??45 the famous sub runner that can be bridged to mono 1000 watts
(these brands are already decided upon, so skip the brand trashing and get to the point... )
You would probably get a more detailed response from the madisound forum or parts express forum. The little I know about the subject says that it wouldn't work out to well because mobile drivers are optimized to use the cabin gain found in your car. like I said try those other forums though, a wealth of info to be had there.
Nothing wrong with it, but there is a problem with just putting drivers in boxes at random. The box volume and port dimensions (if any) are critical to getting a particulkar sound out of a subwoofer. Box size determines how controlled the response will be along with where resonances are, and how big those resonances will be. Every woofer will respond differently to differnet size boxes. Also, you have to have some way of crossing the sub over. Cross overs for car subs will likely be very different from home cossovers, since the car acoustics usually have a big boost from 60 - 120 Hz, so a car sub will cross out at 60 Hz, and the main speakers will cross in at 120 Hz, which will sound bad in a home system. But I don't see anything fundamentally wrong with using automotive drivers in home if you know what you are doing.
Go for it, and let us know the results.
The crossover is no problem, as it is done in the Denon 4806 receiver... subwoofer preamp level out.
The box will definitely be a sealed box, no ports or vents, for smoother response.
I can calculate what the box size should be.
I just sort of cannot find a "home" raw woofer I like, and can find raw car woofers I like.
The woofer I have the 12" Infinity is sort of not terrible, but it could be a LOT better.
The actual speaker in the Infinity sub box is a chunk of junk. Ditto the Klipsch 5.1 computer speaker broken down trash box.
The retail subs I see have not got anything better anyway in the price range I can afford.
(A nice Martin-Logan $3,000 or a B&W $3,000 would be ok... but out of the money range I am willing to throw at the problem.)
(am I in a nasty mood or what?)
So far the Canton's do well, they just need the last low freq. from 40hz down to 22hz.. enough to give the bass a bit of feel.

Before you adventure into Autophilia, check out Steve Deckert's Audiophile Wicked One and see if it might fit your requirements (and wallet).
One of the best bargain woofers ever:

Just make sure the box is the right size.

Good luck!