South Dakota ? Oil prices plunged below $56 a barrel Wednesday as awful numbers from retailers and a dismal outlook from automakers lent yet more evidence that the U.S. and the rest of the globe will slash its energy use.

The Energy Department said it expects U.S. consumption of petroleum to drop more severely than any time since 1980 next year, with gasoline use dropping by another 3 percent. Its Energy Information Administration on Wednesday said 2009 petroleum consumption is projected to sink by a further 250,000 barrels per day, or 1.3 percent, more than twice that projected in its previous outlook.