About The 2-second rule: fixed point, counting, formula: which statement is WRONG?
The rule of thumb is (speed:2)+10%, so it depends on speed: 27.5 m at 50 km/h, 44 m at 80 km/h, 55 m at 100 km/h.
The legal rule is open: 'be able to bring the vehicle to a stop within the distance you can see and that is clear.'.
The 2-second distance is time times speed (rule of thumb: speed divided by 2, plus 10%): 27.5 m at 50 km/h, 55 m at 100 km/h — twice as fast is twice as many metres, not four times.
With the fixed-point method, you start counting as soon as you yourself reach the point, not when the car ahead passes it.
Explanation
trap: applying the fixed-point method backwards. Book p.123 - 'if the car ahead of you passes a marker post, you count how long it takes before you yourself reach that post.' Counting starts with the car ahead, not with yourself