vvn
are you sure or not? Highway is usually a 1 lane drive? What do you mean by that?
Having live in NZ for so long, i can tell you, most of the highway are not 1 lane drive.
When you refer to east side of the island and west side of the island, i believe you are referring to South Island. The east side in the main trunk road and obviously, it would be easier to drive.
You mentioned about the roads being hilly, what do you expect? NZ is a hilly country, so there will be bends and uphills and downhills. That makes driving fun right? Who wants to drive straight road for hours and hours.
Do worry, 99% of the roads are sealed. The 1% of the roads are roads that most tourists dont go. Where can you find the 1%? simple, up to the ski fields. If you want excitment, drive on Crown Range Road. Best view you ever get in the South Island.
For those who are worried about driving, very simple. Let me quote you what Transit NZ said "The more important roads of the state highway network have generally been given single digit numbers while the less important state highways within regional areas are usually given two digit numbers ."