Local competition is among factors cited by fuel company Mobil for reported prices that vary in Auckland by as much as 7.6 per cent today.
Observers reported Mobil prices for 91 grade petrol that ranged from 196.9c per litre in Birkdale on the North Shore to 211.9c/l on Karangahape Rd near the central city.
That's a difference of 15c/l, which makes a fill at K Rd price 7.6 per cent dearer than at Birkdale.
But Auckland prices at other companies were higher and lower: 217.9c/l at the Z station near the airport, and 189.7c/l at the Gull self-service at Wiri.
A BP email leaked to news outlet Stuff revealed a management plan to push up prices.
The plan was to counter dwindling sales in Ōtaki, where the price of fuel was 20c dearer than in Levin, which is 17km away.
Instead of reducing the price in Ōtaki to make the station more competitive, the manager proposed an increase for the whole region, with the expectation that competitors would match the new price.
In a statement, BP said its move was in response to local competition and discounting having become "unsustainable".
"Petrol prices in New Zealand are highly competitive and we adjust our prices in response
to local competition, particularly in instances where discounting has become
unsustainable, which is what occurred in the lower North Island last year."
Mobil Oil New Zealand refused, on grounds of company policy, to discuss price differences between Mobil stations.
Answering a Herald question, the company said the socio-economic profile of a location is not a factor that influences Mobil's petrol prices.
Mobil's lead country manager, Andrew McNaught, noted that New Zealand's fuels industry is a free market.
"Mobil strives to offer competitive prices in each segment of the market in which we operate at all times," McNaught said.
New Zealand is a "very tough, competitive petroleum market". It required ongoing investment to improve the local fuel supply chain and meet growing demand.
"Pump price, promotions, discounts, service station facilities, and customer service are key factors to attract and retain customers.
"Fuel prices are influenced by a number of factors, including product cost, exchange rates, transportation, retailing costs and local market competition.
"Setting retail prices is thus a balancing act between the immediate effects and influences of the market versus the longer-term outlook for our business and the industry.
"Within New Zealand motorists are increasingly benefiting from discounts off the advertised board price, such as those offered via in-store promotions and loyalty programmes.
"We are continuously finding ways to improve our consumer offer, including innovation and providing consumers with high-quality fuel products and excellent service in a safe and responsible manner."