I'm travelling with my younger sister & her bf. They're driving up the country and are routinely doing 100mph on the motorways etc which feels overly fast to me. Context: I'm from an overseas country where speed cameras and checks are routine and most people just stick to the speed limit.
Is this the norm in the UK? If not, would you breach the peace and say anything? It doesn't help that they're continually play fighting while driving too which doesn't add to the feeling of safety...