I just discovered that Siri now has an option for New Zealand English! I had it set to Australian before this, (who doesn't love a cool accent?) but in honor of our forthcoming trip I decided to change it up. Disappointingly, it sounds pretty much the same. It turns out the new update was more focused on giving Siri the ability to understand a Kiwi speaker than sounding like one, and not with total success:
While Siri's voice retains something of an Australian twang, it understood a New Zealander saying "Can I get some fish and chips for six tonight?" with no issue. An older version of Siri often interpreted the phrase as "sex tonight".
But further tests showed the new Siri was still prone to this error, just not as often. Neither version properly understood a strong Kiwi accent asking for help fixing a "deck".
http://www.stuff.co.nz/technology/apps/67665965/apples-siri-gets-new-zealand-english-version