frankv: I'd go further and say that NZ needs a 4-lane 100kph divided expressway from Auckland to Wellington, and further. As soon as you have 2 lanes in each direction, differences in traffic speed become a non-issue.
Anyone who has driven in America will know what I mean.
I drove through seven States there late last year sticking to the speed limit with the cruise control set to it on the freeways and interstates and sat in the slow lane the whole time, I was getting passed by everyone.
On the i5 interstate going through Utah the speed limit was 80mph which I was driving at and I was getting passed like I was standing still by nearly everything, including truck and trailer units. Interesting to see the signs on the side of the Interstate saying "Speed monitered by aircraft"
This. I tried to be a good tourist, but on second day I just decided to be part of the flow. It's "fun" travelling 140-160kmh for hours without major turn. No wonder they want autopilot on their cars :D Gas burns like water in the desert, but hey it is cheap as chips over there :)