Indeed, the only flaw we can see in the EPA’s announcement is that it doesn’t go far enough. Partly, this is because the agency only has authority to waive the current legal requirement for a year; partly it’s because “biofuels are a key part of the Obama administration’s . . . energy strategy,” as EPA Administrator Gina McCarthy put it on Friday. What’s really needed is a repeal of the ethanol mandate, which was enacted in a different time, on the basis of projections about energy markets that have not panned out. More efficient fuel-conservation measures, such as a gas-tax increase, would let broad incentives, not politics, determine the best way to move cars and trucks while meeting energy security and environmental goals.