This article investigates the impact of petrol price cycles on consumer purchasing behaviour in Brisbane, Australia. By comparing the sales volume data to the gross retail margin—the difference between the recorded retail price and the average terminal gate price, relationships between price and sales volume are examined. This study found that the price cycle observed in some Australian cities has become less predictable and hence it is more difficult for motorists to take advantage of the heavily discounted petrol around the trough. The study uses fuel purchase data for the period between July 2011 and March 2013, collected by the Royal Automobile Club of Queensland.