During his last presidential bid, Barack Obama committed to modernizing the cars we drive, so our transportation needs don't mean a dependence on foreign oil. He said his policies would promote more hybrids, more vehicles running on biofuels and a revival of the electric car.

Here we'll evaluate his progress on a specific promise from that larger clean-car agenda: Obama said half of all cars purchased by the federal government would be either plug-in hybrids or all-electric by 2012.

The pie chart below comes from annual reports by the General Services Administration on federal vehicle acquisitions. Since the year isn't finished, we can't reference the 2012 report, but the data give enough information to rate this promise. Plug-in hybrids and all-electric vehicles represent a tiny sliver of overall vehicle acquisitions for Obama's first three years in office -- so tiny, in fact, it's hard to see its thin blue slice in the chart.



You can see a more detailed layout of year-by-year vehicle acquisitions by fuel type below, including the last three years from President George W. Bush's administration. The federal government bought many times more all-electric or plug-in hybrids and many times more conventional hybrids under Obama than under Bush.

Obama's pledge focused on plug-in hybrids and electric cars, which accounted for less than 1 percent of all federal vehicle acquisitions in 2011. That's also true across all three years Obama has been in office. Either way, it's a far cry from half.

It's worth noting that the government buys other types of vehicles that do not rely on pure diesel or gasoline: About 45 percent of all vehicle acquisitions in 2011 ran on alternative fuels such as hydrogen, compressed natural gas, liquid petroleum gas or a "flex-fuel" mix that is 85 percent ethanol.

The last time we updated this promise, we mentioned the administration's progress on buying more hybrids. In 2011, gasoline and diesel hybrids -- not the plug-in kind -- accounted for 7 percent of all federal vehicle acquisitions. In the two years before Obama's presidency, hybrids represented less than 1 percent of all vehicle acquisitions.

We wondered why Obama focused on plug-in hybrids (think Chevy Volt), rather than conventional hybrids (think Toyota Prius). Was one really more effective in meeting Obama's clean energy goals?  

"It really is a better fuel choice on many levels," said Jay Friedland, director of legislative affairs for the pro-electric car group, Plug In America.

We found evidence to back up Friedland's claim on websites for the U.S. Energy Department's Alternative Fuels Data Center and research lab for renewable energy. The typical plug-in hybrid has a battery that you charge from an outside source, often by plugging it into your house. This battery then powers the car at low speeds over short distances, i.e. city driving. If you turn up the air conditioning, travel long distances or crank up the speedometer, the plug-in's gas-powered internal combustion engine might kick in. So, the gas tank only comes into play when the primary batter is being overtaxed. The Energy Department's research lab for renewable energy says plug-in hybrids consume less fuel and emit less greenhouse gases than stand-alone hybrids.

We think it's worth giving Obama credit for gains he's made in diversifying the federal fleet. Overall hybrid purchases have increased under Obama, and more than half of all vehicles purchased by the federal government last year ran on some kind of alternative fuel. Still, plug-in vehicles represent less than 1 percent of those purchases, nowhere near Obama's campaign pledge. We rate this a Promise Broken.