To boost use of electric vehicles, the Obama administration is installing charging stations for government vehicles in Washington, Detroit, Los Angeles, San Diego and San Francisco.

The General Services Administration plans to buy 116 plug-in electric vehicles, including 101 Chevrolet Volts. That's a tiny fraction of the 650,000 vehicles the GSA manages, but Energy Secretary Steven Chu and other officials say the purchase is an important symbol of the administration's commitment to reduce U.S. dependence on foreign oil.

President Barack Obama has called for a one-third reduction in oil imports by 2025 and wants to put 1 million plug-in electric vehicles on the road by 2015.

"Diversifying our transportation fleet with hybrids, electric vehicles and other alternative fuel vehicles is a critical element in President Obama's long-term plan to break our dependence on foreign oil and invest in America's growing clean energy economy," Chu said at a news conference Tuesday at the Energy Department.

The purchases announced Tuesday are expected to cut gas usage by almost 29,000 gallons a year, saving taxpayer an estimated $116,000 and reducing greenhouse gas emissions by 257 metric tons, said GSA administrator Martha Johnson.

In addition to the extended-range Volts, the GSA said it will but 10 battery electric Nissan Leaf vehicles and five Think City EV models from Finish EV startup.

In a related announcement, the White House formalized a directive Obama issued in Mach ordering the government to purchase only fuel efficient cars and trucks by 2015.

A memorandum issued Tuesday directs federal agencies to develop practices to move toward the 2015 goal and come up with a plan to determine the best size of their vehicle fleet.

Under a separate executive order, Obama has called on the federal government to reduce gasoline usage by federal vehicles 30 percent by 2020.