Definition
Safe following distance is the gap to keep behind the vehicle ahead to stop without crashing if it brakes hard. It depends on speed, road surface, reaction time and braking capacity.
Key facts
- The 2-second rule: pick a fixed point on the road; if you pass it before counting two seconds after the car ahead, you're too close.
- In rain or fog, double the rule to 4 seconds.
- Outside built-up areas, vehicles over 3,500 kg must keep at least 50 metres behind.
Practice real questions on this topic
Free DGT 2026 test with exam-style questions and explanations. No signup. Or explore the free DGT test in English hub for everything in one place.
In the DGT exam
- Outside a built-up area, the black car in the left lane has finished overtaking. It can safely return to the right lane, and neither traffic nor road conditions justify staying on the left. May it normally remain in that lane?
- There is light fog, but visibility is sufficient to overtake or abandon the manoeuvre safely. All other rules are met and overtaking is not prohibited. Does fog alone prevent overtaking?
- On a section with visibility so restricted that you cannot check whether a U-turn would endanger other road users, may you make it?