Unlike the fog lamps, which should already be used as soon as visibility is poor, the rear fog light should only be switched on when visibility is less than 50 metres. The reason is that the rear fog light emits 30 times more light than the rear lights and so when visibility is better, it has the effect of blinding the drivers behind. The reflecting marker posts along the motoway are a useful means of judging distance, as they are spaced 50 metres apart in many countries. Rear fog lights, which are now specified for all cars, have been around since 1967. In 1970 there were 3,000 accidents caused by fog obstructing visibility, whilst twenty years later, the number of accidents of this type according to the statistics of the German Federal Office of Transport was down to 1,457.* Keep a good distance. If you get too close, you will get sprayed with salt and snow. Not only can this severely hamper your vision, the salt will also get into the wheel housings and cause corrosion.

• Give these vehicles plenty of room and do not get in their way with  risky overtaking.
• If you overtake, remember that where the snow plough pushes the snow to one side, a small bank of snow will form. Drive over this at an oblique angle to avoid having all your wheels stuck in the deep snow at the same time.
• Do not overtake snow ploughs working in tandem. Remember that the road behind them will be clear and safe. Overtaking is dangerous, because the snow plough at the front will be driving on the overtaking lane and there will be only a short distance between both snow ploughs. Here again one also has to expect banks of snow, plus a considerable amount of snow and salt spray on the windscreen.Overtaking snow-clearing vehicles doesn't get you to your destination any quicker. If you are ahead of the snow plough, you are on a snow-covered road and that means you have to drive more slowly anyway.