All the dash cams we tested have a GPS receiver that makes it possible to record the location and speed of the car. This is done via text that is placed over the video image; it shows the location as coordinates. A few manufacturers also record the speed and location as metadata in the video files, allowing you to use your computer to directly see on Google Maps where you were at the time.
As mentioned before, a few cameras offer the possibility to warn you when you leave the driving lane (on accident). The optical recognition of the white stripes is not flawless with any of the tested models. The markings on the road are not recognized that well when there is a lot of shadow and when it is raining cats and dogs the recognition usually does not work. The device also does not know if you leave the driving lane on accident or deliberately, meaning that you also receive warnings when you purposefully change lanes.
The function that warns you when you are too close to the car in front of you also does not work immaculate. Sometimes the car in front is miles away and you still receive a warning. The opposite happens as well: if you are nearly in the trunk of the car in front the dash cam might not even notice.
A lot of cameras also have a G-force sensor; this makes it possible to automatically make an emergency recording when registering heavy shocks. The sensitivity is usually configurable which is useful so that in a faster car the camera does not start an emergency recording with every bump.
We tested all cameras by mounting them behind the windscreen of a car at the same time and driving under different circumstances. We tested on very sunny days where there was a big difference between light parts of the image and shadows, but also in cloudy weather and during the evening in the dark. The video below gives an impression of the image quality of the different cameras.