Several posts have emphasized that they believe you should pay the ~$15 extra per day to get rental car insurance. We have found that in most places if you have a good credit card like an AMEX Platinum and use that card to rent the car, that they will cover your insurance per the terms in their credit card as well as the fact that your own car insurance covers you as well. Is this not true in New Zealand as well?
I had a problem with Europa car in Europe (Austria) where they charged me $1200+ for a minute chip. AMEX cover this entire amount even though I claimed it was a fraudulent chage. I had assumed the same would be true in Australia and New Zealand.