Yes, the main point is that I pay more attention when driving faster on a freeway. One need only take a road trip in Australia to see how ridiculous low speed limits on open roads are. 110 kmh limit with, yes, very strong enforcement in place, in a completely rural area with few cars around, no people, no pedestrians, on a long drive (it's ten hours from Melbourne to Sydney with basically nothing in between).
Result -- zone out on cruise control, look at your phone, talk to others in the car, etc. Focus on the road? Nope.
Australian traffic camera tolerances are also set ridiculously low, and there are far too many variations in limits.
I fully support 50kmh urban street limits, but the open road sections should have a day/night limit, where the day limit is 130, like most of Europe and some parts of the US. There should also be limits to how often a speed limit can change in a single stretch of road, and highway speed zone changes should have a minimum of three signs at even spacing to indicate the change approaching, at the spot and one more reminder.
There should also be a ban on concealed traffic cameras - getting a fine long after the event has very little effect on the behaviour, apart from generating feelings of injustice.
Exactly -- sure, you can still hide behind a truck and go 100 km/h all the time -- but most cars efficiency sweet spot is around 130 km/h, and driving at that speed leads to more dynamic, occasionally passing trucks, etc.
When I consistently drive at the speed limit (in the Netherlands, 120km/h) I have to fill up every 4 working days. When I consistently drive 100 km/h I only have to fill up every 5 working days. Takes 20% longer but the tank also lasts 20% longer.
Depends on the car. If you have a tiny engine, then it will use large amounts of fuel at high speeds. If you have a large engine, it will use less. My personal experience:
Peugeot Partner 2.0 HDi - 6-7l/100km when driving in city traffic, 12-13l/100km when driving at 140km/h,
Land Rover Discovery 3 4.4L V8 - 15-16l/100km when driving in city traffic, 9-10l/100km when driving at 140km/h.
Basically your engine should stay below 3000rpm - if you have to keep it at 4000rpm just to maintain a certain speed then it's too much for the engine and it's not being efficient.
110 isn't that much different to the US's 75. There is much stronger enforcement though. I spent six weeks driving around the US, multiple hours most days, and I was generally 0-5 mph above the speed limit... but I didn't have to look at the speedo. Came home, and it was painfully obvious just how much of my attention was split watching the speedo like a hawk because people can and do get fined for doing 64 in a 60 zone. And the fines aren't trivial.
Result -- zone out on cruise control, look at your phone, talk to others in the car, etc. Focus on the road? Nope.