Aucklanders could save between $260-350 a year on petrol bills, just by shopping around.
The Commerce Commission's latest fuel price monitoring report for July to September last year finds price differences of up to 30-cents-a-litre within cities.
It also found retail prices did not fall as quickly as the cost of importing fuel, pushing up importer profit margins by more than 60-percent, forcing the Energy Minister to intervene.
The AA's Terry Collins spoke to Charlotte Cook.
