Why Is This Feature Useful at Night?
Imagine driving along a dark road while another vehicle follows behind you with bright headlights.
Your eyes have adjusted to the darker environment, so a strong reflection from the rearview mirror can be distracting and uncomfortable. Using the night position reduces the intensity of that reflected light.
The goal isn’t to eliminate your view behind the vehicle. Instead, the design gives you a dimmer version of that view so bright lights are less bothersome.
When Should You Use the Night Position?
The feature is most useful when headlights from vehicles behind you are producing noticeable glare in your interior mirror.
You don’t necessarily need to switch it every time you drive after sunset. If there is little traffic behind you or glare isn’t a problem, the normal position may provide the clearest view.
If glare becomes uncomfortable, however, moving the lever can quickly reduce it.
Should You Move It Back During the Day?
Yes. The normal daytime position generally provides a brighter and clearer rearward view.
The night position intentionally makes the reflection much dimmer, so leaving a manual mirror in that position during daylight can make the rear view unnecessarily difficult to see.
If your rearview mirror suddenly seems unusually dark during the daytime, check whether the lever was accidentally moved.
Why Doesn’t My Car Have This Tab?
If you’ve looked under your rearview mirror and can’t find a lever, nothing is necessarily missing.
Many newer vehicles use an automatic dimming rearview mirror instead.
These mirrors can use sensors and electronic technology to detect lighting conditions and reduce reflected glare automatically. The exact system varies by vehicle.
Some auto-dimming mirrors also include buttons, indicators or other controls, while others work largely without driver input.
Manual vs. Auto-Dimming Mirrors
The basic objective is similar: reduce uncomfortable glare from lights behind the vehicle.
A manual day/night mirror accomplishes this mechanically. You move the small lever yourself and the mirror changes the reflection reaching your eyes.
An auto-dimming mirror uses an electronically controlled layer that can darken when the system detects conditions associated with glare.
The automatic version is more convenient, but the traditional mechanical design has one major advantage: it is extremely simple.
Does Moving the Tab Move the Whole Mirror?
It may feel as though you’re simply tilting the mirror, but the mechanism is designed so that switching between positions changes which reflection reaches your eyes while maintaining a useful rearward view.
This is also why the mirror should first be adjusted correctly for your normal driving position.
The little lever isn’t intended to replace proper mirror adjustment.
Adjust Your Rearview Mirror Before Driving
Before driving, adjust the interior mirror so you have an appropriate view through the rear window while sitting in your normal driving position.
Make adjustments while the vehicle is stationary rather than trying to reposition the mirror while concentrating on traffic.
If your vehicle has an unusual mirror system or electronic controls, consult the owner’s manual for the manufacturer’s instructions.
What If Moving the Tab Doesn’t Seem to Do Anything?
There are several possibilities.
First, the difference can be much easier to notice at night when bright lights are visible behind the vehicle. In daylight, the effect may not be immediately obvious.
Second, your vehicle may use a different mirror design. And if the lever is loose, damaged or doesn’t remain in position, the mirror may need to be inspected.
Avoid forcing a control that doesn’t move normally.
Once you start noticing details like this, you’ll find that cars contain several small features hiding in plain sight.
