The Commerce Commission's investigation into the retail fuel market shows it's most expensive on the West Coast, Queenstown Lakes and South Wairarapa at $2.20 or more per litre.
Most other parts of the South Island and chunks of the North Island - including Wellington - are expensive too, paying $1.99 to $2.09 per litre.
Timaru, Upper Hutt, Kapiti and Auckland are also costly. But the rest of the North Island, and Waimate in Canterbury, pay the least to fill up.
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South Islanders are unimpressed with the findings, telling Newshub on Tuesday it's "unfair" and that it "sucks because we're still going through the earthquake problems".
Here's what your average $2.20 a litre is paying for: The majority, 97 cents, is on taxes, while the actual fuel costs 83 cents. Petrol companies make 34 cents, with a tiny 6 cents discount for you on top.
The revelations follow the Government ordering its consumer watchdog, the Commerce Commission, to do a deep-dive into what's fuelling high fuel prices.
"Our instinct was certainly that New Zealanders were being fleeced at the pump and the Commerce Commission has confirmed that is true," Prime Minister Jacinda Ardern said on Tuesday.
The Commerce Commission wouldn't go as far as saying "fleeced" with Commission chair Anna Rowlings saying it's "not a term I would use".
But the watchdog did find that a lack of competition is driving up fuel prices across the country.
"If competition was better facilitated, consumer could be paying less for fuel than they're currently paying," she told Newshub.
Z Energy, BP and Mobil control 90 percent of the fuel supplied to New Zealanders, with smaller companies buying fuel from them.
And because the major companies share infrastructure, reducing costs, they potentially freeze out new rivals
Gull is the only other fuel importer in the country.
Gull general manager Dave Bodger said when Gull opens, "all the players in the market drop their prices and that's great - you don't have to shop with us, you just get better value on fuel".
The Prime Minister said the Government wouldn't be axing further tax increases on fuel.
"What we've seen happening in the market far outstrips what's happening with excise [tax]," she said.
National leader Simon Bridges disagrees. He pointed the blame at the Prime Minister, labelling her the "Fleecer-in-Chief".
The commission also found that discount and loyalty programmes could be disingenuous, with bigger discounts offered as prices also went up.
"I will give [New Zealanders] a guarantee we will not stand by while they continue to be fleeced it's not right," Ardern said.
"We as the Government stand ready to act."
But not just yet: the commission's full report will be released in December and Ardern said the Government will wait to see it before it acts.