I can say with pretty strong confidence that its due to 1. On long trips this situation can get pretty interesting if you end up finding groups of other cars that are on the highway for similar amounts of time. You could say that the group takes on a dynamic similar to a herd hiding from a predator.
The riskiest position for a car is the leader position and the last position, as these are the easiest positions to get picked off by the police. Most people want to go faster, but don't want to get caught. Often times you'll see people alternate the leader position as a way to share the risk and acknowledge that the other driver is taking greater risks by taking the leader position.
The riskiest position for a car is the leader position and the last position, as these are the easiest positions to get picked off by the police. Most people want to go faster, but don't want to get caught. Often times you'll see people alternate the leader position as a way to share the risk and acknowledge that the other driver is taking greater risks by taking the leader position.