I've had a Nextbase camera in the LR for 2 years - its plugged into the power socket but on the LR that is ignition switched.
I use a 32Gbyte SD card giving about 4 hours of video and set up to overwrite and set up for 3 minute files. The camera has a button that you press to write protect a given file and has an accelerometer that will automatically protect the file if it detects a bump.
It has GPS - that's a double edged sword. If you drive like a nutter all the time, probably best you don't have it. But, its there to show the speed, direction and location. The video on its own doesn't easily show how you're driving. Most of the time if you're hit, it will be from behind or the side. The video won't prove much. Although I've twice recently been hit from behind while stationary.
Even if you don't have GPS and you're involved in an accident at speed, the police have the ability to assess your speed to within 1-3 mph. Just having the video is sufficient for them to assess your speed and confirm their calculations. Its actually very easy just involving some basic maths. If you're concerned about the camera giving evidence against you at any point, better you don't have it at all whether or not it has GPS.