Staff members at BP referred our inquiries to Harvey Green, owner of the stations on Anzac Parade, Fitzherbert Ave and Taupo Quay, but he could not be contacted.
Gull's New Zealand retail manager, Graham Stirk, said his company had a simple process for pricing: "We keep our costs low and pass on the savings to our customers, easy as that."
Katherine Klouwens, group communications manager for Foodstuffs New Zealand, said Pak'nSave worked as a commission agent on behalf of Mobil which set its fuel price in accordance with local market conditions.
"Both companies drive to deliver their customers the most affordable prices possible. Wanganui is a particularly competitive fuel district and Mobil ensures that Pak'nSave Wanganui can offer fantastic fuel prices keeping us extremely competitive over our competition," she said.
A Caltex Victoria Ave staff member said their prices were handed down to them by price support at head office.
"But at the end of the day it's just competition," he said.
Mark Stockdale, senior policy analyst at the AA, agreed and said such difference in prices was "proof positive" of a competitive market.
"Often, motorists don't think there is competition but this proves there is. It's great to see price competition out there."
He said smaller independently owned service stations could set their own prices, rather than having it set by a parent company, and that Gull's consistent low prices had led to "the Gull effect".
"It seems wherever there's a Gull it tends to lead to competition in prices, with the bigger competitors in the neighbourhood having to match them.
"If you see a cheaper price then go for it - just shop around," Mr Stockdale said.
