Finally, we've got some good news on petrol prices

AUSTRALIAN motorists are not being ripped off as much at the bowser, according to the latest report out from Australia's consumer watchdog.

Petrol prices in the five largest cities (Sydney, Melbourne, Brisbane, Adelaide, and Perth) decreased by 3.8 cents per litre (cpl) in the September quarter 2016 to 114.2 cents per litre.

But prices in Brisbane remain higher than other major cities.

The 114.2 cents average across five cities is lower than the 118.0 cpl of the previous quarter and was 7.5 cpl lower than the annual average of 121.7 cpl in 2015-16, the Australian Competition and Consumer Competition says.

The international refiner margin - the difference between the price of refined petrol and the price of crude oil - is now close to the annual average refiner margin of USD 8 per barrel over the last 20 years.

"International factors continue to strongly influence the price at the bowser. A drop in refiner margins in the last quarter has helped to push prices down locally," ACCC Chairman Rod Sims said in a statement.

"Australian motorists have benefited as prices have fallen, which will be especially welcome as we move into the busy holiday period."

In the September quarter 2016, taxes represented around 44 per cent of the retail price of petrol in Australia.

This is much lower than in other developed countries, the ACCC says.

"Despite these lower prices our message to all motorists is: continue to shop around and reward those retailers offering the best-priced fuel. This will help you, and also bring more competitive tension to the market."

"Improved price transparency from initiatives such as FuelCheck, an online tool with real-time prices for almost every retail site across NSW which commenced in August 2016, as well as existing apps (such as Motormouth, GasBuddy, and those of the petrol retailers), is giving motorists the ability to easily compare prices and get the best deal."

In the September quarter 2016 average retail prices in Brisbane were 115.2 cpl, 1.3 cpl higher than the other four largest cities.

"Although prices remain higher than other cities, and this must annoy Brisbane motorists, they are facing the lowest price difference with the four other largest cities since 2009," Mr Sims said.