The Automobile Association says a drop in oil prices and improving exchange rates should spur petrol companies into dropping prices at the pump.
It is the second time in a week the motorists' lobby group has criticised the fuel industry for refusing to lower prices.
The Automobile Association says petrol retailers should alter fuel prices to reflect the market changes, just as they would if oil prices rose dramatically.
AA spokesperson Mark Stockdale says the industry could drop the price of 91 octane at least another few cents a litre.
But Chevron, which owns Caltex and Challenge, says the AA doesn't have access to the industry's cost sheets, so its comments are unfounded.
Chevron says all petrol retailers monitor prices daily and if they can drop them, they will.