It's as up to date as the information provided by others (as I can't know when stations open, close or adjust their hours).
I'd suggest in the first instance you use a Garmin GPS and the NZ Open Street Maps. All points of interest are taken from the community project Zenbu (www.zenbu.co.nz) which anyone can edit after establishing an account (email address and password). I note 24hrs in the opening hours field and this is dragged through to the maps. Anywhere you are, search for fuel in the gps, put in the key phrase "24hr" and you'll find the closest 24 hour stations. Naturally they may be unmanned, and it's only card facilities.
Failing that, buy a bike with a 600km+ range
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