At many gas pumps, the gas contains 10 percent ethanol. The Environmental Protection Agency has approved using 15 percent ethanol, but it will be some time before pumps in the metro area see any change.
So far, the higher ethanol blend is approved only for use in cars made in 2007 or later, since that's what's been most tested.
EPA Assistant Administrator Gina McCarthy says this was just the beginning of a broader renewable fuels market.
"This decision was a step in the direction of allowing more renewable fuels into the market. It is by no means an assurance that that market will happen quickly," she says.
Like many states, Virginia and Maryland would have to change their regulations to either allow or make easier the use of higher ethanol blends. The District doesn't regulate it one way or another, but there are plenty of other obstacles. Gas retailers say it's cost-prohibitive to add another pump at each station just for newer cars. And at least one major oil company has said it has no plans to offer the higher ethanol blend until more testing has been done.