Work out safe following distance instantly with clear inputs, formula shown and shareable results.
The two second rule works at any speed because the gap scales automatically with velocity. Double it in the wet, quadruple or more on ice, and increase it again for a heavy vehicle whose braking distance is far longer than a car's.
Following distance
distance = speed (m/s) x time gap; two seconds dry, four wet, ten or more on ice
Because it self-adjusts with speed. Two seconds is 61 m at 110 km/h and 17 m at 30 km/h, both about right.
Pick a fixed marker the car ahead passes and count. If you reach it before finishing 'only a fool breaks the two second rule', you are too close.