We live in Whangaparaoa and have a Gen 1 ZS EV. We don't pay too much heed to the GOM. We look at its consistent 16 kw/100km over 20,000km. WLTP range is over enthuiastic, as Gavin on Ecotricity on Youtube says Way Less Than Predicted. Take the WLTP and knock off at least 15% for a real world figure.
All depends on car and driving style.
With the Mk1 ZS EV there has been one big issue: the NMC battery has buffers at both the bottom and top end that you don't get to use. But as far as I can tell they never adjusted the WLTP range (or GOM) to reflect that (that still uses 100% battery capacity). In practice the WLTP 263km were mostly unachievable, more realistic would have been 240km, accounting for the reserved parts of the battery.
Then over time the NMC battery degrades. Mine was down to about 95% by the time I sold it with 28' km. GOM did actually reflect that and gave less range, even after a reset of the trip metres.
Fast forward to the Mk2 ZS EV: the LFP battery has a much smaller buffer set aside (only at the bottom end to avoid over-discharge, none at the top end, it can charge to real 100%). Also so far (12'km) I can not notice any degradation.
That means that most of the time my GOM predicts more than the 320km WLTP range, and that the predicted range of around 340km is actually achievable in my day to day driving.
Mind you: I live in Perth where it doesn't usually get freezing cold, and of course there are variations day to day: if winds are strong, my range drops. As it should (physics).