A man fills his car with petrol at a She

MELBOURNE, AUSTRALIA: A man fills his car with petrol at a Shell service station in front of an advertising sign showing their alliance through cheaper petrol prices for customers of supermarket chain Coles Myers, in Melbourne 13 July 2004. Australian petrol retailers warned that trading alliances linking supermarket giants Woolworths with Caltex and Coles Myer with Shell were creating a duopoly threatening the long-term future of other oil companies in Australia. The price war sparked by the alliances are squeezing the margins of Australia's other oil refiners, BP and Mobil who have privately said they would consider leaving the Australian market if the supermarket alliances continues to damage their bottom line, leaving the market to Shell and Caltex. AFP PHOTO/William WEST (Photo credit should read WILLIAM WEST/AFP via Getty Images)