When fog has cleared you should turn off your rear fog lights. What is the reason for this?

When fog has clear… — To prevent drivers behi…

The answer options

To allow brake lights to work
To maintain engine power
To stop draining the battery
To prevent drivers behind being dazzledCorrect

Why the other options are wrong

“To allow brake lights to work” is a distractor. It does not meet the standard the question is testing, which to prevent drivers behind being dazzled does. Picking it in the real test costs a mark you cannot get back, and with a pass mark of 43 out of 50 you only have seven to spare.
“To maintain engine power” is a distractor. It does not meet the standard the question is testing, which to prevent drivers behind being dazzled does. Picking it in the real test costs a mark you cannot get back, and with a pass mark of 43 out of 50 you only have seven to spare.
“To stop draining the battery” is a distractor. It does not meet the standard the question is testing, which to prevent drivers behind being dazzled does. Picking it in the real test costs a mark you cannot get back, and with a pass mark of 43 out of 50 you only have seven to spare.

Why that is the answer

Rear fog lights are exceptionally bright so that your vehicle can be seen in thick fog. Once visibility improves, these high-intensity lights will glare and dazzle drivers behind you. They can also mask your brake lights, making it difficult for following traffic to react when you slow down. The Highway Code states you must switch off your fog lights as soon as visibility improves.

What vehicle handling covers

· Front and rear fog lights and the 100-metre visibility rule
· Descending steep hills in a lower gear and engine braking
· Traffic calming, humps, and driving over tram rails
· Night driving, dipped headlights and dazzle from oncoming traffic

Mistakes learners repeat on this topic

· Leaving rear fog lights on after visibility improves
· Coasting downhill in neutral to save fuel
· Using full beam on a lit motorway or behind another vehicle
· Accelerating between speed humps instead of holding a steady speed

Instructor tip: Any question with fog in it usually turns on the 100-metre rule — check visibility before you check the lights.

How this comes up in the real test

Questions from vehicle handling appear throughout the 50-question multiple-choice section, and the wording changes between versions. Learn the rule rather than the sentence: the DVSA can ask the same point from the opposite direction, and a memorised answer falls over the moment the phrasing moves.

The pass mark is 43 out of 50, so seven wrong answers is your entire margin. If a whole category is shaky, run the topic practice below until you are getting every question right for the right reason, then go back to full mocks under the clock.

Practise Vehicle Handling Sit a full mock test