DVR

You don't want a DVR that uses a hard drive in a moving vehicle. That is what most of the multi-channel security systems use. Hard drives having moving parts and you aren't supposed to bump them around while they are recording. Think of the needle on the hold record players when somebody would slam the door next to the record player. But as others have said, dashcams record to a memory card and have no moving parts. I bought one for my motorhome and with a 64gb memory card it records about 9 hours before looping back over it. And really, you don't need that much memory.