Russia, the world’s largest producer, can no longer rely on the same oil revenues to rescue an economy suffering from European and U.S. sanctions. Other producers such as Iran, Venezuela and Nigeria are either at war or crippled by political and economic policies are set to lose a lot of money from the decision of Organization of Petroleum Exporting Countries last week to let the force of the market determine what some experts say will be the first free-fall in decades.
Why is the petrol so cheap then? Well, demand for oil has been falling - because of the euro zone’s stagnation, Japan's recession and China's slowdown - while output has been rising, largely thanks to America's shale boom.
So an oil glut has been created, which was reinforced last week when the oil producers of OPEC - to the great surprise of many - didn't cut their output target of 30 million barrels a day.
Anyway, the important point is that an oil price fall represents a transfer of cash into the pockets of consumers, via lower prices for petrol and all goods and services where energy is a big component of the price.
What's the net benefit to the global economy of the tumbling oil price? Well, economists estimate that a 40% fall in the oil price, if sustained, would add something over 0.5% to global economic growth, perhaps as much as 0.8 %.