Core: Calculating overtaking distance: the 60-formula and the blind spot

The overtaking-distance formula reads (Book p.143): 60 x your own speed, divided by the speed difference between you and the vehicle ahead. If you drive 80 km/h and the vehicle ahead drives 25 km/h, the difference is 55 km/h: 60 x 80 : 55 = 87 metres. If the vehicle ahead instead drives 60 km/h — a SMALLER difference of 20 km/h — the result becomes 60 x 80 : 20 = 240 metres. The smaller the difference, the longer you need to overtake, not shorter. Before you actually start overtaking, you check the blind spot in three fixed steps (Book p.143): first the interior mirror, then the left exterior mirror, and finally over your left shoulder. Only that last step reveals a vehicle invisible in any mirror. Two distance rules belong to the overtaking manoeuvre itself (Book p.145): when overtaking pedestrians and cyclists, keep a lateral distance of at least 1.5 metres, and before overtaking keep sufficient distance to the vehicle ahead (the 2-second rule), so it can see you coming clearly. On the motorway overtaking is usually safely possible (Book p.147), but limits still apply there too: the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed — 'usually safe' is not a free pass for unlimited-duration or unlimited-speed overtaking.