MarkA, 15 million! My city has only about 650,000, and spreads out to about twice that, but traffic is nuts and you have to drive a ways to find a nice country road.
I just read “The Lost Man”, by Jane Harper, a very descriptive and interesting novel set in the Outback. Sounds like there might be a gazillon square miles with zero traffic!
you might enjoy it.
Good luck in NZ; I have an old US Navy shipmate who retired to the North Island and loves it. I wish I could do that.