Which light setting should I use when driving in mist and heavy rain?

Hello Paul, when driving in mist or heavy rain, should I use the full beam, dip beam or fog lamps? Should the same settings be used whether it is night or day? Christopher

Hello Christopher, although anything to make you more visible is better than nothing, sidelights are seriously inadequate for driving in any poor-visibility condition, night or day. They are only useful at night, in clear conditions, when a vehicle is parked.

When conditions are not clear (mist or heavy rain or thick dust, night or day) the default setting is dipped headlamps. They are not always optimal, but they are adequate and are never the wrong light to use.

 During daytime, no light setting will significantly improve your ability to see. The only but absolutely essential job of your lights is to make you more visible to others. Dipped headlamps will achieve that without dazzling oncoming drivers (or unduly distracting you with reflected glare).

 If the fog or dust is so thick that even oncoming headlamps are hard to see until the last moment, full beam headlamps can be considered because they are more powerful and because the gloom is so dense, they are less likely to dazzle. Case by case, test which gives you the better view ahead.

At night, as well as indicating your presence and position to others, the right settings are essential to your own ability to see where you are going.

 Dipped headlamps are still the go-to option because full beam lights will impair your vision (with reflected glare). They will simply make the wall of mist and things you can already see brighter, but make the pupils of your eyes contract and not enable you to see any further forward.

Fog lamps 

That factor is the rationale for specialised fog lamps. They are mounted low because the mist is often thinner nearer the road surface so the beam goes further (this does not apply in dust), and they are bright but do not dazzle because their beam is downward, flat and wide. If your car has purpose-designed fog lamps properly mounted, they can always be used in conjunction with dipped headlights if helpful.

 In especially heavy fog, they can be used instead of headlights to minimise reflected glare and optimise forward illumination “under” the mist. But you must then keep your sidelights on so that those behind you can see your tail lights.

Other principles for driving in fog include slowing down, regularly wiping your screen, and also trying not to focus on what you can see (your own bonnet) but instead on what you cannot see deeper in the mist. 

What is the use of roof rails and wing fitted ‘baby mirrors’?

On SUVs functional and is there a way to safely use them for storage? What additional modifications are required and will Police stop me to inspect what I am carrying? Also, the baby mirror on SUVs that are located behind/above the front left headlights of SUVs imported from Japan, what are they for and why do the cars have them? Is there a way to safely remove them without damaging the body? JT

Hello JT, roof rails are fibre glass or plastic bars that run along the length of estate or sports utility vehicles (SUV). Roof rails improve a vehicle’s external looks. They also provide basic support for carrying light cargo on the SUV roof if the interior load space is full or you have to carry longer or taller cargo than can fit in your trunk. 

Roof rails add to the practicality of your SUV or Estate car if you have suitable accessories such as cross bars, securing harnesses or the specialised light and compact aerodynamic load box. With these accessories, you can use the roof rails to carry light extra cargo during a road trip when the interior cargo space is full. 

You can also carry bulky (tall and long) but light equipment such as bicycles, golf bags or boxes that are 3/4 the length of your roof and are not too heavy for the roof rails and their cross bars. Roof rails are not heavy duty metallic roof racks designed to carry heavier cargo (50kgs) on bigger and wider SUVs. Cargo for the roof rails should not exceed 25kgs or higher than 1.5 feet to avoid affecting the vehicle aero dynamics or centre of gravity. 

An excessively high centre of gravity for the narrow wheel-based SUV can make it tip over when driving fast through corners. This is why the police will become concerned if your SUV or estate vehicle is carrying cargo that is longer than the car (such as poles) or too high (sofa set, fridge or cooker) on the roof rail.

What you call the ‘baby mirror’ is the small passenger side wing panel convex mirror. It is fitted on the passenger side wing panel front end. This special mirror is designed to provide improved angular visibility of the hard to see front and side views when you are in the driver’s seat. The wing panel convex mirror can help you avoid damaging your tyres and rims on the road kerbs while parking in tight spots. 

You can also use this mirror to avoid falling in the deep roadside trenches when manoeuvring on the side of the road. This mirror is fastened to the wing panel by a screw on bolt. If you decide to eliminate this device, you lose its functionality benefits as well as have to fabricate and paint the wing panel to cover the hole or provision for fastening the mirror.