Many of us have been taught to look over our shoulders when merging or changing lanes. This is a tendency that we must minimize if not eliminate because we do not have this luxury when driving a racecar. We are grateful for the development of containment seats and head-and-neck restraints for driver safety, however these obstruct our head movement (by design) and visibility. Additionally, it is best to maintain some front visibility in your peripheral vision even while scanning around the car and through the mirrors.
Some of us have been taught to adjust our mirrors so that we can see our car’s fenders or door handles as spacial references. These references are unnecessary and use up a lot of the limited mirror space. Additionally, when you see people move forward in their seat to look through their side mirrors, you can be sure that they have not adjusted their mirrors properly. This technique may help drivers see what is in their blind spot but it is better to reduce the blind-spots in the first place.
With proper mirror adjustment, a driver can have nearly 360 degrees visibility without moving his head. At the very least he will reduce blind spots to a minimum so that no vehicle can hide. Some cars have enough mirror and enough adjustment to eliminate blind-spots altogether; in other cars we must be satisfied with minimizing the blind-spot and recognize that they are there in order to avoid surprises.
Many racecars use wide-angle convex or multi-panel rearview mirrors to increase visibility but this is not necessary in a street car. Additionally, many cars designed for the street have very large C-pillars (the sections between the rear window and side windows). Engineers attempt to maximize visibility but oftentimes design and marketing preferences prevail. These large sections of reduced visibility can negate the benefit of a wide-angle rear-view mirror. Fortunately, we can adjust our mirrors to practically eliminate the C-pillar obstruction.
Mirror adjustment is best performed when there are objects behind to use as references. These objects should be roughly one car length behind and half a car width to the side. For safety sake, adjust the mirrors while stationary. We may consider a variety of objects to identify when adjusting the mirrors. Cones or trees are helpful as are walls with identifiable references. However, the best method is to back into a garage or into a parking space with cars in each of the five adjacent spaces around the car: right, right-rear, rear, left-rear & left. A parking space with an island behind is preferred to get the proper spacing. This example will be used for further discussion.
After the proper driving position is achieved (see previous post) adjust the rear view mirror for maximum visibility through the rear window. This is pretty straight-forward. Take note of the items that you can see at the extremities of your rearview visibility. Now we adjust the side mirrors to eliminate the blind-spots. This is the more difficult task.
For continuity sake, let’s start with the driver side mirror and repeat the exercise with the passenger side mirror. The driver side mirror is less prone to blind-spots because of the small angle of reflection and proximity to the driver. Passenger side mirrors often have a convex shape to increase their field of view, which is the reason for the label: “Objects in mirror are closer than they appear.” If you have manually adjusted mirrors, then it is best to find an assistant. Move the mirror inward until you can see the side of your car. This gives us a reference point for our adjustment. Now move the mirror outward until the side of your car is no longer visible.
Next, use the references around you to identify blind spots. In the example of cars in a parking lot, the rearview mirror will likely show the entire rear vehicle as well as some of the right-rear and left-rear cars. You will also notice that you can see overlapping sections of these right and left rear cars in the rearview and sideview mirrors. Now turn your head toward the driver side mirror and turn your eyes toward the adjacent parked car. Using your peripheral vision, identify a reference on the adjacent car as far back as you can see: a rear tire, a door handle, the C-pillar, etc. Next, scan the driver side mirror to see if you can identify that same reference point. Chances are you will not be able to see part of the adjacent car in both your peripheral vision and the mirror. Any section of the adjacent car that is not visible in either the sideview mirror or your peripheral vision is in your blind spot.
Now comes the compromise, which becomes an individual drivers choice. How much are you willing to turn your side mirrors away from the side of your car? If you turn your side mirror out enough to eliminate the blind spot on the adjacent car, then you will create a blind spot between what see in your rearview mirror and what you see in your side-view mirrors. However, this is less critical than you may think. It is very difficult for a whole car to hide in the blindspot between your rearview and sideview mirrors. It is much more likely that a car can hide in a blindspot between your sideview mirror and your peripheral view if the mirrors are not properly adjusted. Being able to see a car in this region is far more critical as a lack of visibility here can cause an accident while changing lanes or passing traffic.
Some people say that they need to see the side of their car in order to gauge the distance from references on the road such as lane markers or curbs. These references should be established in your forward visibility and then gauge your vehicle’s distance from these objects using your spacial awareness. This highlights the initial discomfort we feel when we position the mirrors away from seeing the door handle or fenders: we are reorienting our spacial awareness of our car. It requires more intuition than vision and this is actually a good skill to develop. In any case, when you’re driving at speed on a track you won’t be paying attention to the references behind you anyway.
One important consideration is the way these blind spots affect visibility when backing up. It is much better to move your head to look around and over your shoulders to scan your surroundings at low speed when reversing than to compromise your visibility during the other 99% of your driving duty.
A note for drivers of convertibles: adjust the mirrors with the top up first to insure optimal visibility under all conditions and then verify the visibility with the top down to make adjustments and compromises as needed. Unfortunately, many convertibles have very small rear windows or the rear window has aged to the point of becoming nearly opaque, reducing the effectiveness of the rear-view mirror.
Additionally, some cars have no rearview mirror at all due to thier mid-mounted engine. In this case, the side mirrors must be adjusted to take the place of a rearview mirror. This is a major compromise in visibility and blind-spots are inevitable. Using larger side-view mirrors, convex, multi-focal or fish-eye mirrors can reduce the potential for blind-spots but they also require the driver to adapt to the visual and spacial distortion from such mirrors.