To impose a “low carbon fuel” mandate that requires producers to meet the “maximum technologically feasible and cost effective greenhouse gas emissions reductions,” and reduce the aggregate “carbon intensity” of motor vehicle and other fuels by at least 10 percent by 2020. The bill would impose a “cap and trade” type scheme in which refiners whose fuels do not meet the mandated standard would have to pay ones that did meet it.   Official Text and Analysis.