Global oil prices have come off the boil with expectations the New Zealand pump price will head below $2 a litre.
But a Government report released yesterday on petrol pricing volatility offers little assistance to the consumer if prices spiral again.
Minister of Commerce Lianne Dalziel said one of the key findings was that "retail petrol price rises are not fast to rise and slow to fall".
It was "just perceptions" by the public that the price was fast to rise and slow to fall, "no doubt affected by media reporting of increases".
Petrol rose 60% during the 19 months to July to a record $2.18 a litre.
She said the New Zealand market was fundamentally competitive, recent prices were due to global crude oil prices and a Fuelwatch scheme like Australia's would not work in New Zealand's market, which was different.
The Government has the largest take from prices at the petrol pump - about 36% for a variety of levies and taxes - but Ms Dalziel said there was scope for more transparency surrounding the importer margins, a component of petrol prices equating to 6.6%.
The Government was ploughing all the fuel excise directly back into transport and the country had the fifth lowest petrol prices, including taxes, in the developed world, Ms Dalziel said.
"In New Zealand there has been confusing volatility in the price of petrol, so the Government is going to increase monitoring in order to further improve the transparency of increases," she said in a statement.
Automobile Association spokesman Mike Noon described the report, which the association called for in May, as a "valuable insight" into New Zealand's fuel market and correctly identified that more monitoring was required.
"New Zealand is a small player at the end of a global supply chain and cannot influence the crude oil price.
"Yes, the fuel companies are making billions, but that's not all from New Zealand," Mr Noon said.
Ms Dalziel had identified that the 6.6% importer margin was the only one which could be influenced by the fuel companies but, after costs, their margin was substantially less than the 6.6%, was his understanding.
Global oil prices have risen steadily during the past 18 months, hitting a record $US147.27 a barrel in early July as New Zealand pump prices reached a record $2.18 per litre, largely due to supply and demand concerns, refinery and storm-related issues, worldwide stockpiles and speculators in the market.
During the past two weeks, oil has eased to a three-month low, falling $US30 from the record $US147 to trade about $US117.
During that period in New Zealand there have been four petrol price falls totalling 16c.
The drop came after a weekly report from the US Energy Information Administration showed crude oil stocks in the US, the world's biggest energy consumer, rose by 1.7 million barrels in the week to August 1, well above analysts' forecasts of a 300,000-barrel rise, NZPA reported.
In Australia, the National Roads and Motorists Association (NRMA) has been reported as claiming petrol companies were still charging too much at the pump, despite the biggest fall in prices in four years last week, AAP reported.
Last week, petrol prices in Australia dropped by 6c to an average of A153.5c a litre, the biggest weekly fall since records began four years ago.
But the global price of oil has dropped by $US25 ($NZ34.66) a barrel in the past three weeks.
"Over $US20 a barrel drop, that should have translated into a much greater drop in the price of petrol at the bowsers," NRMA president Alan Evans said.
"It should have been more. They're patting themselves on the back, but they're still ripping motorists off."
Yesterday, North Sea Brent oil futures were trading about $US117.07, Dubai trades for next month at $US114.98 and West Texas International about $US118.54, NZPA reported.
