When driving other people's car, be it family members, relatives, friends or dealer test driver car, often times I would notice that the side mirror of these cars are sub-optimally configured, ie: they are not fully utilized for their function.
The purpose of the side mirrors on a car is to allow the driver to see other vehicles or obstacles that are behind and beside their cars. However, most drivers tend to adjust their mirror to see more "behind" than "beside".
Remember, we also have a rear-view mirror inside the car that lets us see directly out the rear windscreen. So if your side mirror is also looking towards the rear your car, it is essentially duplicating most of the information you are already getting from the rear-view mirror, and at the same time creating a great big blindspot on the side of the car.
image credit : hanselman.com
Most drivers who do this, do it because they want to see the body of their own car so they can observe the relative position between their car and the objects around it. That is all good and well, except this is at the expense of the driver's ability to perceive objects that are inside the blindspot as a result of such configuration.
So how should one configure the side mirrors?
Easy - sit on the driver's seat as your would normally do, with your head and eyes where they would normally be when you are driving. Now turn both mirror outwards until you cannot see the body of your own car on either mirror, then stop. That's it.
Consider this scenario you see in the rear-view mirror below:
There are two cars directly behind me, A and B, parked across the road. Forgive the tall backside of my car and the sloped parking spot at which I am parked, but I promise you there are two cars there even if you could only see their roof.
Now see the differences in the side mirrors
In the right mirror, where I could see car B in almost it's entirety, is the wrong configuration. I already know car B is at my rear by looking at the rear-view mirror, so this adds little useful information. In the correct configuration, I can only see a small part of car B, but I gained a lot more potantial information because now I can see at least 2 more parking bays adjacent to car B.
The same can be observed on the left mirror. Where previously I can see most of car A, after adjusting the mirror I can see a white car parked 2 bays away from it. This is information that I could not see in the rear view mirror.
Translated to everyday driving, this is makes a great difference for the driver's spatial awareness. For example, when another car is overtaking you, once it disappears from your rear-view mirror, it immediately appears in your side mirrors and stay visible until you can observe it with the peripheral vision of your own eyes. This continuity allows you know keep track of traffic around your car with little to no blindspot.
But what if you want to see the body of your own car, especially when reverse parking in tight spots?
Just lean over a bit to either side (just a little bit will do) and voila! you can see your own car again. Because you only turned the mirror just far out enough to not see the body, even just tilting your head slightly should suffice. Once you have gotten used to it, you can turn the mirrors all they way out like me, and the difference is just to lean your head a bit further when reverse parking. That said, each car is different - when turned all the way out in some cars, you may briefly lose continuity when another car disappears from your rear-view mirror and re-appear in your side mirrors. Adjust as your see fit, the important thing is to be able to continuously track the cars around you.
What if you already have a blindspot mirror stuck on your side mirrors?
I had those once, it was promptly stolen days later. Anyway, if you already have a blindspot mirror, then configuring your side mirror properly should allow you to see even further out the sides of your car. There really isn't any downside.
Image credit : accessorygeeks.com
What if my car comes with an electronic blind spot monitoring system?
Again, having fancy equipment to help you stay aware of your surroundings, doesn't take away the advantage of properly configured side mirrors. More over, one should never become over dependent on these safety systems, they are only here to assist, the onus is still on your to drive safely.
Image credit : Volvo
Many may complain that they are not used to it initially because they can't see their car in the mirror. I do know how that feels, but in my opinion most drivers give too little credit to their innate spatial awareness - You don't really need to see your car in the mirror all the time to position it safely, unless you are the driver in the car below:
Of course, every driver is different but why not just give it a try and see the difference it makes.