It is painfully obvious that many so-called drivers are unsure of how to use the rear view mirrors in their automobiles. It is actually a simple concept, but the vast majority of drivers do it incorrectly. The Guys That Know do it right. You can too. The main rear view mirror is located to the right of the driver and mounted on the back of the windshield. This mirror is not what we will be focusing on as it simply looks directly behind the car, out of the back window. Drivers should and generally do adjust this mirror correctly, so that its angle provides a maximal view and the view is roughly centered when the driver glances at it. Easy. The side mirrors are an entirely different story. If the driver is looking straight ahead and occasionally glances at his center rear view mirror there still exists a substantial blind spot on either side of the car. Most driver’s peripheral vision would warn of interference with other vehicles directly to the right or left of the car, but the area slightly behind all the way back to where the center rear view mirror picks up is completely “blind”. Side mirrors were designed to show the driver what is occurring in this blind spot. However, most drivers adjust their side mirrors in a way that prevents them being used to see what is in the blind spot. Instead they are generally carefully adjusted so that the driver has a clear view of the rear quarter panel of the car. I have to ask, when was the last time that you were hit by your own car? Why then adjust the mirrors so that you can see your own car? I’ll suggest that it is just because you didn’t know any better. Let’s fix that.
Courtesy of Car and Driver, here is a graphic that details how to properly adjust your side mirror. In the graphic, you are the driver of the blue car and the gold car is directly behind you. The red car is in the driver’s left blind spot. If the blue car driver were to glance only in his center rear view mirror and then the left side mirror the red car is invisible. Fig. 2 in the graphic shows that the left mirror unhelpfully shows the side of the blue car being driven and the gold car, which is already seen in the center rear view mirror. Basically the improperly adjusted side mirror is useless.