As the WSJ reports today, President Obama has announced the next phase in his administration’s push to improve fuel efficiency on U.S. roads: stricter economy rules for the nation’s fleet of medium- and heavy-duty trucks. That’s a big deal for overall U.S. fuel consumption, because while big trucks make up fewer than 5% of the vehicles on the road, they account for about a quarter of all greenhouse-gas emissions from the transport sector. The move comes after the government introduced ambitious fuel-economy standards for passenger vehicles back in 2012, which aim to cut U.S. oil consumption by two million barrels a day by 2025. But there’s one big challenge in promoting fuel-efficient vehicles: without rising gas prices, it’s getting harder to convince consumers to buy small, economic cars. There’s precedent for what happens to fuel economy when pump prices aren’t part of the […]