It is rather discreet and can easily escape the attention of drivers focused on the road. However, this little black band inlaid on our mirrors can be of great service.
Cars of the 21st century are packed with so much equipment that most motorists don't even use half of them. Worse, among those who do not read the user manual – in other words a lot of people – there are many who do not know the usefulness of such and such a button located on the dashboard of their vehicle.
No question of button on the mirrors, but the latter nevertheless have some functionalities as simple as beneficial. That of the interior mirror allows for example to reduce the brightness reflected in the eyes of the driver thanks to a small latch to be operated. On the two exterior mirrors, it is not a small pull tab but a black band which improves the driver's visual comfort.
On some automotive forums, some new vehicle owners wonder if it is not a sticker intended to protect the glass, as is sometimes done on digital tablets or new watches. It is true that one is entitled to wonder how a line inlaid on a pane can have any utility. Yet it was not placed there by chance. This vertical line, continuous or dotted, has been drawn to provide assistance to the person wedged behind the steering wheel. Often located at three-quarters of the mirror (when starting from the inside out), this small line is in fact used to delimit the flat part and the curved part of your mirror.
This is called an aspherical mirror and is found on most newer vehicles. Looking into the curved part of the window, which is therefore located furthest outside the mirror, the driver sees his field of vision widened. This is in particular what will make it possible to reduce blind spots as much as possible, those few invisible spaces which do not allow the motorist to detect the presence of another vehicle in his rear view mirror. Responsible for many accidents on the roads, especially with two wheels, blind spots can therefore be reduced or even erased thanks to the curve of our mirror windows. You should also know that a small black band makes it easier for the eye to distinguish the flat part to observe what is happening behind and the curved part to widen its field of vision.
And if your vehicle does not have aspherical mirrors, know that it is possible to buy small self-adhesive mirrors in the shape of a sphere that you can place directly on your rearview mirror. You can find them from 5 euros, which is not very expensive to improve your safety in the car...