What is nice in Auckland is that the car rental agencies are really near the exit from the terminal. No need to figure out shuttle buses to remote car rental agencies. The cars seem to be mostly automatic. One of the things I had done is bought the sd card with New Zealand maps for use in my Garmin GPS. I know I could do this with my phone (at least in theory). In retrospect I am not so sure because there were many areas where cell service was not available. I had the Garmin GPS, was comfortable using it and it had a much bigger display that my phone.
Driving in New Zealand is on the opposite side from the United States. I have driven inEngland where that is also the case and did not find it much of an issue. In the past I have had problems navigating the roundabouts but with the GPS it was not a problem. What was a problem was that the turn signal and window wiper levers were reversed from our American cars! I do not know how many times I would turn on the wipers when trying to signal a lane change or turn.
A comment about the roads in New Zealand. They are generally nice – certainly did not see the pot holes common here in Chicago. But the major highways outside the cities are one lane in each direction for the most part. Probably more of a concern was that the shoulder in many cases was small. Making sure you stayed in the center of your lane was a constant concern. Of interest is that often the bridges were just one lane! And quite a narrow lane at that (why did they choose not to build a 2 lane bridge?). The saving grace is that the traffic is light outside of the major cities. It was quite interesting that you could drive quite a while on a major road and not see a car coming in the opposite direction so arriving at these one lane bridges did not cause major delays.
Now for the subject of gas. The stations are not as frequent or as prominent as in the United States. In fact I cannot remember seeing a station that was not in a town. Since the towns are widely spaced you can travel for quite a while without finding a station. There are no indications on the road where the next station may be. Word to the wise - when you leave a city fill up. We actually got this advice from a native of New Zealand and that was what she did.
A recommendation I would make when traveling is get a 220 volt power strip. Finding enough outlets is often a challenge and one has so many things that need to be charged up. And make sure you have the proper plugs – the configuration of the plug is New Zealand is different from others I have seen.
A number of years ago I had gotten my cell phone unlocked so I could get a local sim card when traveling to foreign countries. It was quite easy to get a Vodafone sim card at the airport. Could I have saved a few bucks elsewhere? Maybe. But one of the things I try to do when traveling is reduce stress wherever possible and getting the card right away allowed me to check it off my list immediately.