Reuters: President Barack Obama’s tough fuel economy program for vehicles could put another damper on the struggling ethanol business, because the alternative fuel packs a lower energy content than gasoline. Obama on Tuesday introduced the most aggressive proposal yet to boost U.S. auto fuel economy standards — a bid to reduce vehicle emissions of climate-warming gases. [ID:nN19424837]. The proposal would require passenger vehicles to average 35.5 miles per gallon by 2016. “It’s going …