What is an Auto-Dimming Rear View Mirror?
No more dazzling headlights from the car behind
Simplified animation — not to scale.
In plain English
An auto-dimming rear-view mirror darkens itself automatically when it detects bright headlights from a vehicle behind you. Instead of flipping a manual tab to angle the mirror, the glass dims electronically — reducing glare while still letting you see the traffic behind.
"Imagine wearing sunglasses that automatically get darker when someone shines a bright torch at you, then instantly clear again when the torch is turned off. That is exactly what this mirror does — it puts on electronic sunglasses for you so you are never dazzled."
How it works
The mirror contains two layers of glass with a special electrochromic gel sandwiched between them. Sensors at the front and back of the mirror compare light levels. When the rear sensor picks up significantly more light than the front sensor — meaning headlights are shining directly into the mirror — a tiny electrical current passes through the gel. This causes the gel to darken, reducing the reflected glare. When the bright light disappears, the current stops and the mirror clears again.
Signs of trouble
- ⚠Mirror not darkening when headlights shine from behind
- ⚠Mirror staying dark even when there is no glare
- ⚠Dark patchy or uneven dimming across the mirror surface
- ⚠Electrical warning on the dashboard
- ⚠Dimming function slow to respond or overly sensitive
£100 to £350 total
Always get a written quote. Prices vary by car, region, and parts brand.