Right but we always old adage of "in my day you'd leave the front door unlocked, it was so safe!".I think that's rather different. Most people I think would consider leaving their kids alone as wilful neglect at the ages that they were, especially with a peculiar arrangement of leaving the door unlocked. A car on the other hand, especially a modern one is perfectly safe in itself at 85 mph especially on a motorway that is devoid of the risks such as pedestrians found on slower roads. There's also a precedence set where such a speed wouldn't be unlawful such as on the autobahn.