Following the recommended safety distance (2-3 seconds of travel distance if I recall correctly) is quite difficult in moderate to heavy traffic. If you leave

Following the recommended safety distance (2-3 seconds of travel distance if I recall correctly) is quite difficult in moderate to heavy traffic. If you leave a large enough gap with the car in front, then people will merge into that gap. If you then slow down to create a new gap - people will overtake and merge in again. You end up travelling slower than the rest of traffic, with people overtaking and merging, which creates dangers in itself.