From what I remember, it says in the settlement pack (how to live in nz kit provided by NZIS when you become a resident) that first time residents are allowed to import just about anything they own up to 2 from when they become a resident without paying tax or import duty, so I suppose this applies to cars too. I think you have to have owned it for a year or something like that but there are exceptions such as clothes and the like. I don't think they're looking at receipts just evidence of usuage. So if you're thinking of buying a brand new telly and importing that, the fact that it is new and boxed up is a dead give away and a bit of a no no!

No doubt you'll have to get the car registered and warranted (MOT) and I bet that's neither free nor cheap!