There’s a lot of talk and writing online about the New Zealand government’s super city plan for Auckland.
The correct style for super city is two lower case words. The term is not a name, at least not yet. It is a description. Capitals are only used for proper names, so there shouldn’t be any confusion or question over the term.
Nor is it one word. Over the past twenty years or so there’s been something of a fashion to run words together and separate the component words with a capital letter. If a company or organisation wishes to do that with its name, or the name of a product, it has every right to do so. But there’s no grammatical or logical reason to make a single word out of super city. Would you write Auckland is a BigCity? Of course not.
Fairfax’s Stuff.co.nz web site is confused about this. At the time of writing the newspaper company’s site has an Auckland Super City page which offers every permutation: one word, two words, upper case lower case. The New Zealand Herald is just as confused. Try searching for “supercity” on the site. In fact it adds a previously unseen variation: Supercity, all one word with a single capital.
For clarification and background you may like to read my previous article about capital letters.