# Rearview mirrors **URL:** \ **Category:** Factual Questions\ **Created:** [November 15, 2015, 5:54pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638 "2015-11-15T17:54:02Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![Seanette](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/seanette/32/9139_2.png) [@Seanette](https://boards.straightdope.com/u/Seanette)\ **Post date:** [November 15, 2015, 5:54pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/1 "2015-11-15T17:54:02Z")
I’ve been wondering a lot recently why car side mirrors do not have a night setting, as the inside rearview mirror does. As bright as headlights are getting, it would help a lot. I frequently find that I could read in the glare from headlights behind me, and there’s no way to mitigate the amount hitting me from the side mirrors. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [November 15, 2015, 6:48pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/2 "2015-11-15T18:48:27Z")
Some cars _do_ have side view mirrors that can be dimmed. The Audi A8, for instance, lists one of the features, "power-adjustable, power-folding, auto-dimming, heated exterior side mirrors with memory ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [November 15, 2015, 7:21pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/3 "2015-11-15T19:21:06Z")
> [@Dewey\_Finn](#): > > Some cars _do_ have side view mirrors that can be dimmed. The Audi A8, for instance, lists one of the features, "power-adjustable, power-folding, auto-dimming, heated exterior side mirrors with memory Wow. Can those mirrors do wi-fi with streaming video too? ---
**Author:** ![Claverhouse](https://avatars.discourse-cdn.com/v4/letter/c/13edae/32.png) [@Claverhouse](https://boards.straightdope.com/u/Claverhouse)\ **Post date:** [November 15, 2015, 9:59pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/4 "2015-11-15T21:59:58Z")
I wonder a lot why they still _have_ car mirrors of any type — which are inadvertently detachable outside — and don’t just have built-in external cameras leading to screens on the dashboard or over the windscreen. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [November 15, 2015, 10:13pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/5 "2015-11-15T22:13:46Z")
Because the mirrors are required by government regulations. Tesla and the Alliance of Automobile Manufacturers [have asked](http://www.wired.com/2014/04/tesla-auto-alliance-mirrors/) for this rule to be relaxed to permit exterior cameras instead. ---
**Author:** ![Claverhouse](https://avatars.discourse-cdn.com/v4/letter/c/13edae/32.png) [@Claverhouse](https://boards.straightdope.com/u/Claverhouse)\ **Post date:** [November 15, 2015, 11:57pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/6 "2015-11-15T23:57:12Z")
If government regulations still required a man to walk in front of the car waving a flag, that would not be a reason for keeping an obviated rule. ---
**Author:** ![Terry\_Kennedy](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)\ **Post date:** [November 16, 2015, 5:27am UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/7 "2015-11-16T05:27:10Z")
> [@Claverhouse](#): > > If government regulations still required a man to walk in front of the car waving a flag, that would not be a reason for keeping an obviated rule. In the US, car manufacturers were restricted for many years (after the rest of the world moved on) to using round sealed beam headlights. Eventually the government was magnanimous enough to also allow _rectangular_ sealed beam headlights. Manufacturers are going through the same thing with LED and laser headlights. This is something that pretty much all of the manufacturers care about. Things that only a few manufacturers want to change are even less likely to get changed. Every once in a while a manufacturer gets a limited waiver (for example, Lotus for smart airbags). ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 16, 2015, 7:15am UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/8 "2015-11-16T07:15:59Z")
> [@Claverhouse](#): > > If government regulations still required a man to walk in front of the car waving a flag, that would not be a reason for keeping an obviated rule. Mirrors are also passive devices which work 100% of the time unless broken off. Cameras and video screens are not. Techies are unrivaled in their ability to bend over and suck their own dicks. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [November 16, 2015, 2:01pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/9 "2015-11-16T14:01:54Z")
> [@jz78817](#): > > Techies are unrivaled in their ability to bend over and suck their own dicks. **Moderator Note** **jz78817** , this remark is jerkish and inappropriate for GQ. No warning issued, but do not do this again. Colibri General Questions Moderator ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [November 16, 2015, 2:10pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/10 "2015-11-16T14:10:54Z")
Cars without side mirrors just _look wrong_. ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [November 16, 2015, 2:28pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/11 "2015-11-16T14:28:00Z")
> [@Seanette](#): > > As bright as headlights are getting, it would help a lot. I frequently find that I could read in the glare from headlights behind me, and there’s no way to mitigate the amount hitting me from the side mirrors. I also find that some aggressive drivers will pull a little to the left of the car in front of them either while driving or especially at a light just so that their headlights are intentionally hitting the sideview mirror and reflecting on that person. It’s a jerk move but they’re signaling their impatience for someone to speed up or let them pass. So yes, side dimming is desirable. As for simple mirrors vs cameras, I certainly prefer a video camera in the center back to aide with backing up safely and providing a view that a front mounted mirror can’t. But I’d much prefer my side views remain simple mirrors for two reasons. One, a mirror isn’t as likely to break as it can’t really mechanically malfunction or lose power, and two, cost. I’ll buy it if it serves a superior function but in this case simple is better. There’s no angle I require in the side view that can only be achieved with a camera. ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [November 16, 2015, 2:42pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/12 "2015-11-16T14:42:11Z")
Right, as mentioned there’s already autodimming wing mirrors but it is still a high-end option. It’ll eventually make it to the mainstrean car. One advantage of keeping them as mirrors rather than screens is that an autodimmer mirror failsafes to a plain mirror and you keep the rearview. A failing video screen goes blank. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [November 16, 2015, 4:11pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/13 "2015-11-16T16:11:22Z")
> [@Seanette](#): > > I’ve been wondering a lot recently why car side mirrors do not have a night setting, as the inside rearview mirror does. As bright as headlights are getting, it would help a lot. I frequently find that I could read in the glare from headlights behind me, and **there’s no way to mitigate the amount hitting me from the side mirrors**. (Bolding mine.) Oh, but there is. Yet another advantage to the “no blind spot” method of adjusting your mirrors is that because your side view mirrors aren’t pointing directly back, you should almost never get direct headlight glare in them. Here’s a brief PDF primer on it from CarTalk: [http://www.cartalk.com/sites/default/files/features/mirrors/CarTalkMirrors.pdf](http://www.cartalk.com/sites/default/files/features/mirrors/CarTalkMirrors.pdf) Basically, what you want to do is make it so there’s almost no overlap between what you can see in the rear-view and side-view mirrors. (You shouldn’t be able to see the side of your car at all.) If you do that, you’ll find (depending on the optics of the rear-view mirror) that your side-view mirrors can actually point pretty far out to the sides without missing any visibility. If you have the mirrors set like that, the only time you should ever get direct headlight glare in them is if a car is coming at you from a slightly oblique side street or something. FWIW, I have an older Audi that has some sort of anti-glare side view mirrors (I’m not sure if they’re actually auto-dimming or not.) I adjust my mirrors as I’ve described and I can’t tell the difference between the Audi and my other cars. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [November 16, 2015, 4:23pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/14 "2015-11-16T16:23:23Z")
> [@JRDelirious](#): > > Right, as mentioned there’s already autodimming wing mirrors but it is still a high-end option. It’ll eventually make it to the mainstrean car. One advantage of keeping them as mirrors rather than screens is that an autodimmer mirror failsafes to a plain mirror and you keep the rearview. A failing video screen goes blank. The Subaru Forester has them. I believe the option costs $235, so it’s not that expensive. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [November 16, 2015, 5:47pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/15 "2015-11-16T17:47:07Z")
Man, if only I had brights on my taillights so I could flash the bastards with the super spotlight headlights. Do manufacturers realize that blinding every other driver on the road is not a safety feature? Is it so hard to keep the brights for the backroads and make sure the low beams don’t blind people in city traffic? Or is this a matter of every driver on the road not knowing how to aim their headlights? I’ve seen some cars where the low-beams point straight ahead to blind people, and the high-beams point up at the sky. Is this an issue with owners or mechanics or dealerships or what? Who is making these headlights so bright and why? ---
**Author:** ![Khendrask](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@Khendrask](https://boards.straightdope.com/u/Khendrask)\ **Post date:** [November 16, 2015, 6:31pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/16 "2015-11-16T18:31:13Z")
Clarity. The mirror has infinitely more resolution than any display technology. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [November 16, 2015, 6:50pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/17 "2015-11-16T18:50:23Z")
When backing a trailer, the wide set side mirror needs adjusting for me. Using little stick-on mirrors just uses up the regular mirror view. I prefer mechanical mirrors for reliability reasons. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [November 16, 2015, 7:05pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/18 "2015-11-16T19:05:38Z")
> [@Khendrask](#): > > Clarity. The mirror has infinitely more resolution than any display technology. Not infinitely more. Atmospheric diffraction limits the resolution of optics in air and the resolution of the human eye is a hard limit on the resolution we see. Also, any imperfections in the mirror would limit its resolution. And besides, an HD camera is more than any human needs to back up. We’re not trying to avoid hitting ants or grains of sand. I lean more with the “low tech, doesn’t need to be changed” line of thinking. Cameras might be a worthwhile addition to cars, but I don’t see a need for eliminating mirrors as well. Having redundant backups with unique modes of failure is good engineering. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [November 16, 2015, 7:34pm UTC](https://boards.straightdope.com/t/rearview-mirrors/737638/19 "2015-11-16T19:34:00Z")
One reason (perhaps the only reason) that Tesla and others want to replace the side view mirrors with cameras is that the mirror (slightly) increases drag and they want to squeeze every little extra bit of efficiency they can.