Pioneer AVH-P7800DVD Fork over $2,200 and its yours!

It also has
6.1 channels.
This is a
little cheaper at @600 dollars:
JVC KDAVX2
My local Circuit City sells this JVC (though I can't find it on their website) and I've played with it a bit. There is a menu for bass management i.e. speaker large/small choices but in the wacky world of hi-res audio, that
doesn't mean its settings
also apply to dvd-audio signals. I bring this up because trying to mount a center channel is going to be a major b***h in most cars, so programming the player for "no center" would eliminate this pain in the arse. And AFAIK, Pioneer is the only company selling a
center speaker for automotive use - looks decently built for such a small speaker but don't know well it will integrate with typcially much larger/fuller sounding door speakers.
One irritating feature: there are no menu navigation controls on the head unit's face plate, so you *have* to use the remote for this.
As others have alluded to above, in most mobile environments Dolby/DTS will provide more than enough detail. So personally, I would just use a dvd-video player to listen to dvd-audio discs. That way, assuming the player has bass management like a home player, it would be easy to program it for no center and if needed, "no sub" though make sure the other channels can handle the redirected sub channel's bass. Oh yea, you'll save a lot of money too!
And the few mobile dvd players I've tried *can* play DTS-CDs.
This is a cool product:
DTS-610. It's supposed to output a standard 44.1kHz/16bit digital signal, encoded with the DTS information.
CD burners with digital inputs are cool too.