I've jsut finished installing a security system in a night club. Part of that was one IR cam with it's own illuminating filters. We used this cam:
http://www.trendnet.com/en/products/TV-IP300.htm
It works well technically, although the support and software a ****. We ended up creatign our own interface usign the activeX/Java access methods. It also has a mic htat you cannot disable in the software so you might have to solder it out.
I must say though that those IR LEDs are very powerfull and create a big aptch of light in complete darkness. The also get frightfull hot. Not sure how well this would mount in a car, but it has it's own webserver and computing power, which might come in handy.