No standard tape bassed camcorder will get even close to that length of recording. Therefore
AFAIK your only option is a hard disc bassed cam such as those from JVC and soon to be released by Sony. These can record for even longer than you require, as long as they have a good power source to last long enough. I doubt that any cam battery would get even close, so as you say a 12v connection from a car battery is the only way to go. I would think that most cams can take an external power supply and therefore you shouldn't be too limited by the models that can do what you need.
Mark.