I advise against it. plain and simple.
Now for a little explination. I'm a car audio guy at heart, but I cross some of that over into audio for my bedroom at the college house. I've done numerous setups in my vehicle, and i've had very good results with many different products. I installed a couple dayton titanic's a while back when I was messing with the idea of using HT products in-car. I had great results with it. When I sold that setup, and wanted to do something new, I wanted to do another HT speaker since I had great results last time. So I came across the sw-12.
to say the least, these drivers just arent meant for in car in my opinion. I have good signal coming from my HU, nice cables, sound deadening (entirely too much of it), properly designed boxes, and running the drivers at RMS. I did a direct swap into my bedroom, hooked them (two sw-12's) up to my 225x2@8 ohms amplifier, same enclosure, and it sounds EXTREMELY better. I really dont know how to explain it.
Unless someone else has done the same as me, I have to advise against using this driver in-car, and highly recommend it for a HT or home audio setup.