Gasoline futures tumbled to a six-year low Monday, extending a selloff spurred by growing supplies and concerns about weakening demand. The slump in gasoline futures, which are down 10% this month, is a sign of a burgeoning glut of refined fuel, mirroring the excess supplies of crude that sent oil prices plunging late in 2014. Falling gasoline prices offer a continued benefit for U.S. households, which are expected to save hundreds of dollars each on fuel this year. While crude-oil prices continued to fall through much of 2015, gasoline prices rose as drivers opted to travel more miles and buy larger cars and trucks that require more fuel . At the end of August, gasoline futures were up 14% for the year, compared with a 7.6% decline in crude. Gasoline has since capitulated to the weakness in crude oil, down 13% year-to-date through Monday compared with crude’s 14% fall […]