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.

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

  1. BG
    October 20, 2014 #

    I just use a little rounded mirror on both side views and it works great.

  2. Laura Elkins
    November 13, 2014 #

    That is interesting with the mirrors,I will try that when I go out to my car,never heard that before,Thanks,Also with the engine light coming on,the gas cap is the first thing I check,because Thank God if that is all it is,and that has happened to me before,so what a relief,but if not have it checked out by your mechanic,but your right do not panic.

  3. Uday
    November 15, 2014 #

    I will adjust my mirrors right away. Thank You Esurance.

  4. Greg Bayley
    November 21, 2014 #

    Ford did work on forward and rear visibility in the 70's using the same premiss of setting mirrors to blind spot targets. I developed a physical test method to validate the design requirements using a laser and full scale targets representing vehicles in blind spots. Requirements never seemed to get integrated into regular design requirements. Matt Reid at UMTRI was working on similar design requirements more recently.

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