You will probably see a few terms that you haven't come across before if you have never rented a car in New Zealand. Here are some important ones:
What it is: ACC (Accident Compensation Corporation) is New Zealand's automatic no-fault personal injury insurance for anybody who is injured in an accident while in the country. It will cover injury-related medical costs while you are on New Zealand soil, and you don't have to apply for it beforehand - you're covered automatically.
What it does: ACC covers medical costs for absolutely anyone who is injured while in New Zealand, including overseas visitors. It's funded partly by government contributions and partly through levies on products like fuel or vehicle licensing fees.
What it is: If you're from the USA, you may be familiar with the term "deductible", meaning the amount of money you pay before your insurance company begins to cover your costs when you need to make a claim.
In New Zealand a deductible is known as an excess.
What it does: Let's imagine your rental car agreement provides insurance with a $1000 excess. The car gets dented during your trip, and it will cost $2500 to repair. As long as the terms and conditions on your rental agreement have been met (more on this later), you will only need to pay $1000 towards the repair bill, and the rental company will pay the remaining $1500.