WASHINGTON - The federal government has invested billions of dollars over the past 16 years, building a fleet of 112,000 alternative-fuel vehicles to serve as a model for a national movement away from fossil fuels, according to the Washington Post. But the costly effort to put more workers into vehicles powered by ethanol and other fuel alternatives has been fraught with problems, many of them caused by buying vehicles before fuel stations were in place to support them, a Washington Post analysis of federal records shows.

More than 92 percent of the fuel used in the government's alternative-fuel fleet continues to be standard gasoline. And, the federal program - known as EPAct - has sometimes increased gasoline consumption and emission rates, the opposite of what was intended.

The Postal Service illustrates the problem. It estimates that its 37,000 newer alternative-fuel delivery vans, which can run on high-grade ethanol, consumed 1.5 million additional gallons of gasoline last fiscal year because of the larger engines. The vehicles that would allow the agency to meet federal mandates were available in six- and eight-cylinder models -- not the four-cylinder variety it traditionally purchased. Alternative fuel was used less than 1 percent of the time in 2007-2008, according to the Washington Post.

The Post analysis shows that at least 2,341 flex-fuel vehicles were placed in seven states with no E-85 stations, and in Puerto Rico, where the situation is the same. Hawaii has the greatest share, with more than 1,000 flex-fuel vehicles purchased or leased by various agencies, mostly military. The U.S. Navy tops the list. The Navy has more than 670 flex-fuel vehicles on three islands. Not one of the sedans, SUVs, or trucks has ever operated on E-85.

Another shortcoming of EPAct was that it did not require fleet managers to track vehicle locations. The fleet grew, but no one knew how it was taking shape. This discouraged private investment in fueling stations because industry needed better data.

The GAO said its analysis showed that future improvements will rely on better data. And it is time for government to reassess the original vision for the fleet, the agency said.