Next time you’re sitting in your car, take a moment before starting the engine. Look at your rearview mirror and you’ll notice a small tab at the bottom, usually made of plastic and matching the mirror’s frame color. This isn’t just a random design feature — it’s a practical tool that most drivers never use, but really should.
Our vehicles are filled with features that often go unnoticed, even when we drive the same car every day. Many of these overlooked elements serve important safety functions that can make your driving experience safer and more comfortable. The tiny lever on your rearview mirror is one such feature that proves especially valuable during nighttime driving.
Why proper mirror positioning matters before hitting the road
Before turning the key in the ignition, you should always take a few seconds to make sure everything is properly adjusted, even in a vehicle you drive daily. This includes checking your seat position, steering wheel height, and mirror alignment.
For the side mirrors, make sure they’re positioned to minimize blind spots — not too low and angled just right to give you maximum visibility. The interior rearview mirror should provide a full view of your rear window, giving you complete awareness of what’s happening behind your vehicle. (Getting these settings right takes just seconds but dramatically improves your safety on the road.)
The “secret” feature hiding in plain sight
Let’s focus on that interior rearview mirror. By regulation, all vehicles must have a left-side mirror and a center mirror. If the center mirror isn’t present, there must be one on the right side. Most cars, however, come equipped with all three.
Almost every rearview mirror includes a small tab or lever on its underside. If you can’t immediately spot it, run your hand along the bottom edge of the mirror housing — you’ll find it easily. This seemingly insignificant control serves an incredibly practical purpose, especially when driving after sunset.
What does this mirror tab actually do?
This little tab functions as an anti-glare system. Its operation is remarkably simple: flipping it changes the mirror’s position to prevent the headlights of vehicles behind you from causing dangerous glare in your eyes.
Have you ever driven on a dark road, especially a two-lane highway, with someone following too closely behind you? Their headlights shine directly into your mirror, creating a blinding reflection that makes it hard to see what’s ahead. This is not just annoying — it’s a serious safety hazard.
The solution is elegantly simple. By flipping that small tab, you change the mirror’s angle so that headlight beams reflect toward the ceiling instead of directly into your eyes. The mirror still shows you what’s behind, but without the intense glare that can temporarily blind you.
How the anti-glare mechanism works
The technology behind this feature is called a prismatic day/night mirror. It works by having a wedge-shaped piece of glass with reflective coating on both the front and back surfaces. In normal “day” position, you’re looking at the reflection from the back surface, which gives you the brightest image.
When you flip the tab to “night” mode, you’re now seeing the reflection from the front surface, which reflects about 80% less light. This significantly reduces glare while still allowing you to see vehicles behind you, just with reduced brightness.
In newer vehicle models, some manufacturers have replaced this manual system with auto-dimming electrochromic mirrors that darken automatically when they detect bright light from behind. These high-tech versions use sensors and special gel-filled glass that darkens electrically when needed.
When to use this feature
The anti-glare tab is most useful in these situations:
– Driving at night on poorly lit roads
– When being followed by a vehicle with overly bright or misaligned headlights
– On two-lane highways with oncoming traffic
– In heavy traffic where headlights from multiple vehicles behind you create constant glare
Using this feature takes virtually no effort but can make a significant difference in your nighttime driving comfort and safety. Next time you’re driving after dark, give it a try — you might be surprised at how much it helps reduce eye strain and improve visibility.
Simple features that make a big difference
This mirror tab is just one example of the many thoughtful design elements built into modern vehicles that often go unnoticed. Taking a few minutes to familiarize yourself with these built-in safety features can make your driving experience safer and more enjoyable.
So next time you get behind the wheel, take a moment to look around your vehicle. You might discover other useful features you’ve been overlooking for years. That small plastic tab on your rearview mirror may seem insignificant, but it’s there for a good reason — to help keep you safe on the road.
