Also you will have to pay GST on the import of the car if you haven't owned it for 12 months before you leave for NZ.
The GST cost is based on the price paid for the car overseas (so you'll need to make sure you still have the receipt) plus the shipping and shipping insurance costs less a little bit for depreciation.
More info
here.
And you won't be allowed to put anything in the car as the car is likely to be going onto, and coming off, a number of different ships on the way over so theft is a distinct possibility.