50 is the new 40

I was driving with my wife, who, by the way, is an excellent driver. However, she does not always obey the speed limit as much as I do. That is to say, that, when it comes to the speed limit, she drives like everybody else. We were driving down a road near us with 2 lanes in each direction and a 40 m.p.h. speed limit. She was driving about 50 m.p.h. What amazed me was that, if I hadn't looked at the speedometer, I would have thought that she was driving 40. I would have thought this by the way the cars were zipping by her. It wasn't amazing to me that cars drive fast but that 50 seemed like 40 because cars were still zipping by. I wonder if anyone would have tailgated or given her the finger if there wasn't a lane to pass.