Wow! Just found out that the Sony PlayStation 2 EyeToy Cam is the perfect Webcam for the CarPC!!
640x480x 30 Frames/sec, veeeerrryy sensitive at night, very fast and sharp, beautifull colors!
And: it has a built in microphone!
I found the drivers on bittorrent. I seems there is a D-Link VGA Webcam built in the EyeToy case.
I found the cam for about 20$ bundled with eyetoy play 2