you probably are already aware of the many dash-cam DVR's out there: http://www.amazon.com/2-5-inch-Vehic...dp/B0053DDNW6/
but it sounds like you want something bigger/better...
check out the 4 channel anti-vibration unit here: http://www.geovision.com.tw/english/...mpactV34ch.asp
looks like it can use their wifi module: http://www.geovision.com.tw/english/...ifiUSB7711.asp
says it features:
- Retrieve video by date, time and event
- Remote playback
under "options" it lists a 12v power adapter.
most of these type of units can also do scheduled/automatic FTP uploads (which would get the data to your home network as requested). this unit does also support DHCP, so it should work pretty easily with your home wifi.
i've never used anything from that company, but i have been looking at video server/dvr's lately so i just happen to know of them.