Convex mirrors don’t belong on new cars

Many RACV members have contacted us in recent times with complaints about the increasing use by vehicle manufacturers of wide angle or convex mirrors. Some even go to the extent of replacing the convex glass with a piece of regular flat-plane mirror glass cut to size from a glazier. I agree with their frustration.

Convex mirrors provide wide angle vision but this benefit is outweighed by the myriad of more potentially dangerous issues.

Over the past ten years or so, vehicle manufacturers have progressively introduced convex rear view mirrors on the outside of new cars. The argument presented for the convex mirror is that it provides a wide angle of vision and therefore less likelihood of not seeing a vehicle in the so called blind spot between a driver’s peripheral vision and the view rearward from the internal rear view mirror. This solitary and erroneous reason for their existence is considerably outweighed by a myriad of more potentially dangerous issues.

First of all the reality of convex or wide angle mirror means the objects viewed in that mirror are distorted by the degree of curvature and appear smaller than they actually are. For this reason vehicle manufacturers who initially only fitted convex mirrors to the left hand side of the vehicle included a warning in the glass that “objects are closer than they appear” which tells you drivers are required to compensate for the misleading visual reference.

Drivers are often confronted with dangerous judgement calls when relying on convex mirrors.

These convex mirrors now appear regularly on the right hand or driver’s side of the car and the reference to objects being closer than they appear is disappearing. As a result drivers are often confronted with dangerous judgement calls when relying on the convex mirror.

Firstly there is a visual difference between looking down the road and looking in the mirror which requires the eye to adjust to a different focal reference, which can cause confusion and a delay in response. Secondly the vision is distorted and the other car is actually closer than it appears which can result in close calls or miss-judgement of traffic when making lane changes. At night the concave mirror exaggerates the headlights of following vehicles which can cause dazzling and also a delay in eyes adjusting to the lights. And, finally any raindrops on a convex mirror are severely distorted and can completely negate the mirror’s function all together, so you have no rear view mirror!

Convex mirrors are so unreliable that trucks do not have them on their own and instead use both large flat-plane mirrors for correct visual reference

Convex mirrors are so unreliable that trucks do not have them on their own and instead use both large flat-plane mirrors for correct visual reference and convex mirrors for a wider view because of their height and the need to see all around the vehicle. Even some respected European vehicle manufacturers with an eye on safety, such as Mercedes Benz have used both types of mirror, flat-plane and convex in the same standard size external rear view mirror.

The internal rear view mirror essentially provides a good view of vehicles and the road behind.

This propensity to adopt a convex mirror has arisen principally because drivers have rarely been taught to use the flat-plane mirror correctly. The internal rear view mirror essentially provides a good view of vehicles and the road behind. Why then do drivers persist with angling their two outside mirrors to view the same piece of road? If those outside mirrors are angled out slightly more, so that they start where the internal mirror ends then they provide a view of the erroneously called blind spot. The result is that the drive never loses sight of a passing vehicle for example or one in the adjacent lane. Vehicles behind and those conducting passing, move from the rear view to the correctly angled flat-plane side mirror to the driver’s peripheral vision.

Those who snigger at this setup need only look at a racing driver with a helmet on. Unable to turn their head to any great degree they rely on their mirrors and their mirrors are set so they can see all aspects of the road and vehicles around them. Their life depends on it.

Do you disagree? See ‘Convex mirrors belong on all new cars‘ to read about a different view on this topic.

Images iStock.com / Anika Salsera

Written by Ernest Litera
July 14, 2016