Car audio components will tend to be 4 Ohm, while most HT gear is 8 Ohm compatible. They are also designed for a smaller, enclosed environment, not an HT. Will it work? Yes. Will it be great? Probably not.
I'm currently using a pair of Infinity 5 1/4" car speakers as the center channel in my custom built ET center. They sound pretty good too. When wired in series, two 4 ohms become an 8 ohm load. I will, however, be replacing them with the woofers of an Onkyo center and the tweeter from a Cerwin Vega CV-5 because I want to put the Infinity's back in my Fiat. You can use auto speakers but with varying success. I just happen to have a ton of car speakers lying around. The proper inclosure is critical. Just for fun, I took the 4" mids out of the Onkyo center and put Polk GX-4's in their place. Not bad, but I really didn't audition them for very long. In the long run you're better of sticking with the HT stuff. Gene