Forget Everything You Know About Rearview Mirrors

Turns out many drivers have been adjusting their side and rearview mirrors incorrectly. Find out if you’re one of them (and how to fix it).

rearview mirror

It all began with Dorothy Levitt back in 1906. Not long after she suggested that women should carry a small handheld mirror to “hold aloft from time to time to see behind while driving,” rearview mirrors became a fixture on cars.

Cut to modern times: we now have blind-spot monitoring technology available in cars ranging from Chevrolet to Mercedes-Benz. But, according to expert George Platzer, blind spots can be avoided by adjusting our mirrors properly.

Platzer’s thesis, “The Geometry of Automotive Rearview Mirrors – Why Blind Zones Exist and Strategies to Overcome Them,” recommends a way to adjust your mirrors so you can eliminate blind spots (of course, you have to wade through some complex equations first).

We’re creating blind spots with our mirrors

Whoever taught you to drive probably told you to adjust your outside mirrors so you can see the sides of your vehicle reflected in them. Where this conventional wisdom came from is lost in the mists of time and probably has nothing to do with pioneering motorist Dorothy Levitt.

According to Platzer (who, by the way, has graduate degrees in Physics and Automotive Engineering), that traditional method pretty much guarantees 2 large blind spots, each one big enough to hide a car. That’s because the outside mirrors’ field of view overlaps with the inside mirror’s significantly — and that means all 3 mirrors are essentially looking at the same space behind you.

3 mirrors, each with a specific job

Let’s divide up the jobs of the 3 mirrors found on most modern cars. The inside rearview mirror gives the best view directly behind your vehicle. Although large rear-seat headrests or your passenger’s heads can get in the way, this inside mirror generally provides a clear and wide view of the cars behind you, including those traveling in adjacent lanes on multilane highways.

The sole job of the outside mirrors, then, is to reveal vehicles traveling alongside and slightly behind you. That means you should adjust these outside mirrors so there’s just a tiny bit of field-of-view overlap with the inside mirror. When the car that’s passing you moves outside the view of the inside mirror, it should start to appear in one of the side mirrors. Then, when it starts to move out of the view of that mirror, it should be visible in your peripheral vision.

How to eliminate blind spots

So, how can you perform this ideal mirror adjustment while seated in your parked car? Platzer suggests following these 4 easy steps:

  1. From the driver’s seat, position your head against the driver’s-side window, and then adjust that side’s rearview mirror so you can just barely see the side of your vehicle.
  2. Next, position your head to the right, more or less over the center console, and do the same type of adjustment for the passenger-side mirror.
  3. Once your side mirrors are adjusted properly, make sure your rearview mirror is centered for optimal view of what’s behind you.

It may sound awkward, but it works. With properly adjusted mirrors, you can minimize those quick over-the-shoulder looks before you change lanes, and, instead, simply glance in the outside mirrors and use your peripheral vision to detect cars alongside you.

Change your driving behavior

Still not convinced? Well, according to the National Highway Traffic Safety Administration, there were 1.5 million injury crashes in 2011 and 9 percent involved lane-change maneuvers. While blind-spot monitoring technology is improving this stat, you don’t need to invest in a new car (or rely on technology alone) to stay safe.

My advice: consider changing the way you adjust your mirrors. You have little to lose but old habits.

And, as a precaution, continue to look over your shoulder until you become comfortable with this method. Over time, you may find you can rely almost solely on your mirrors. It’ll be easier on your neck … and you may just save it!

You can read more from Neil Szigethy on his blog carknack.net.

18 Responses to “Forget Everything You Know About Rearview Mirrors”

  1. Brooke Rollinger
    October 1, 2013 #

    Enlightening stuff! Thanks Neil!

  2. Claire
    October 1, 2013 #

    Could you still see something as small as, say, a motorcycle?

  3. Pat A.
    October 1, 2013 #

    I learned this a long time ago from a Veteran Driver, and it really does work! :)

  4. nudeyorker
    October 1, 2013 #

    I'll give it a try. But here's a hint: don't drive with your head against the side window!

  5. Will Corbin
    October 1, 2013 #

    That tip was in Popular Science or Popular Mechanics a LONG time ago…

    Good to see it surface again!

  6. Ian O'Handley
    October 1, 2013 #

    My Father taught me this trick in high school and I've used it ever since (now 22 yrs. old.) Glad the big whig professionals are finally putting it out there for everyone!

  7. Brooke Rollinger
    October 2, 2013 #

    Tried it on the way home yesterday and it worked PERFECTLY!!
    Thanks again, Neil!

  8. angela mckinnon
    October 4, 2013 #

    Just brought a new car and the 1 2 and 3 sure did help me set my mirror lol I had not tried adjusting my mirror this way awesome!!!!

  9. Rick Gammel
    October 6, 2013 #

    Some things just need repeating.
    I just found out that 9 out of 10 people don't know they can turn off their beeping horn when locking or unlocking their car with a remote. We can use some more quiet in this world.

  10. Rich
    October 17, 2013 #

    The "move your head" left and right method might work, but here is an alternative. Adjust your seat and sit in your normal driving position. Center the inside rear view mirror image on the view directly behind you. Without moving your head, adjust the side mirrors until their views abut the view behind.
    In your driveway, a shrub or tree at the edge of the inside mirror's view should be just barely off the view seen in your side mirror. Verify your mirror settings on a straight highway: while moving only your eyes, you should see a passing car slide from the inside mirror's view to the appropriate side mirror's view. If you're passing someone, the car slips from the side mirror to the inside mirror.
    In practice, leaving a slight (1/4 car width) "gap" between the mirror views widens your side viewing angle and lessens any blind spot between your side mirror and your peripheral vision. The "gap" (i.e., slight blind spot) in the view should not be large enough to hide a motorcycle.

  11. barney
    October 23, 2013 #

    While the quoted method works – for standard personal vehicles – it is intrinsically useless for most commercial vehicles, as well as many personal van/suv vehicle types. Driver attention will always trump mirror arrangements.

  12. Greg
    November 2, 2013 #

    First… Park your car along side a kerb adjacent to a driveway (on the opposite side of the road) no mirror adjustment will pick this up, this is your blind spot also. Second… by adjusting your mirrors out more you increase thin slivers of vision blocks behind your vehicle (depending on your top to side mirror ratios) Third.. you have no point of reference with objects or cars near you. Fourth..all mirrors are not focally correct.

    This system does not eradicate the total blind spot area. This would be very unwise to get this notion of comfort in mirror checking over real blind spot checks with our teenagers.

    I suppose next we will be telling motorbike riders they don't need to check their blind spots.
    I know who I would prefer to sit next to as a passenger in a car during heavy rain and humid conditions while they were changing lanes.

  13. Benny
    November 5, 2013 #

    Dang! I learned this on my own from driving 3 hrs round-trip everyday in bumper to bumper traffic. I swore by it when people said I was crazy. I'm emailing this to all those b@st@rds right now!!!

  14. Toonsrider
    November 19, 2013 #

    I always (in ALL weather) keep my rear windows down a half inch or so, I can hear when a car, or truck is coming up beside me. The little stick-on bubble mirrors help, too.
    Where can I get a FLAT replacement mirror for the right outside mirror? Because of very tight parking I have no choice but to use my outside mirrors.

  15. Paul G
    December 15, 2013 #

    Be careful if you live in a state that allows motorcycles to lane split. I grew up in a state that doesn't allow lane splitting and I was taught to adjust my mirrors as directed by this article. But now I use larger blind spots so that I can see lane splitting motorcycles

  16. Aurelio
    December 19, 2013 #

    My neck really appreciate this info. Thanks

  17. ruqi
    February 24, 2014 #

    not helpfull at all

  18. Rosalind Dunlap
    September 3, 2014 #

    Iam going to do that first thing tomorrow.sounds good .

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