A dashcam is usually fitted once and then left alone for years. All the more reason to take your time with the installation. Position and alignment decide whether footage later shows something or merely points roughly in the right direction.
The right spot on the windscreen
Mounting behind the rear-view mirror has proven itself. The camera hides nothing you need for driving, because the mirror occupies that space anyway. At the same time it sits centrally, which keeps the perspective symmetrical and makes distances easier to judge.
It matters that the camera sits within the area the wipers clear. In rain the glass in front of it otherwise stays smeared, and the footage becomes unusable exactly when visibility is already poor.
Note
Your own field of view comes first. A device that restricts the view ahead is mounted in the wrong place, whatever its image quality.
Alignment: two thirds road
The most common mistake is a camera aimed too high. In such footage the sky takes up half the frame, the automatic exposure adjusts to it, and the road sinks into darkness.
As a guideline: roughly two thirds road, one third sky. The bonnet may be just visible along the bottom edge. That looks unremarkable but helps with judgement, because it shows how far away another vehicle actually was.
Check the alignment after fitting with a real drive rather than while parked. Only in motion do you see whether the framing works and whether the mount twists over bumps.
Cables that stay out of the way
A cable hanging loose is annoying and, in a crash, dangerous. Route it along the headliner to the A-pillar, behind the trim there and on down to the footwell. Trim panels can be released with a plastic wedge without breaking anything.
Keep clear of airbags while doing so. Many vehicles have an airbag inside the A-pillar, and a cable trapped there becomes a projectile if it deploys. When in doubt, run the cable along the outside of the trim and fix it with clips.
After fitting
Check three things: is the clock right, is the framing correct, and does the camera start reliably when you turn the engine on? That check takes two minutes and answers the question of whether the camera actually runs when it counts.
Repeat it regularly. The article on the monthly quick check summarises what to look at each time.
Mount: adhesive pad or suction cup
Both work, they simply have different weaknesses. An adhesive pad holds permanently and does not shift, but it comes off only with effort and leaves residue. A suction cup is flexible and suits changing vehicles, yet it loses grip in heat and cold and occasionally drops off exactly when nobody is looking.
If the camera stays in the same vehicle permanently, the adhesive pad is the more dependable choice. For rentals and travel a suction cup is more practical; there, however, what the article on dashcams in a rental car describes applies as well.
Check the mount occasionally with light pressure either way. A camera that has quietly rotated has been filming past the scene for weeks.
