The retail price of 91 octane petrol is now below $2 per litre at all outlets.
Shell, BP and Gull cut their petrol prices by 3 cents a litre on Thursday, and the price of diesel by 8 cents a litre. They were followed by Caltex. Mobil did so on Friday morning.
The retail price of 91 octane is now $1.99.9c per litre and 95 octane is selling for $2.04.9 a litre. The retail price of diesel is $1.71.9 per litre.
Gull's general manager Dave Bodger says diesel prices have reduced because large refining margins on the fuel have eased.
National Australia Bank economist Gerard Burg says a reduction in demand in the United States is a key reason for the price falls.
He says large cutbacks in China's industry for the Olympics have also had an impact, but that's expected to change once the Games end.