On March 22, the Environmental Protection Agency (EPA) began receiving comments on a proposed weighting factor to be used by car manufacturers to figure out how much flexible-fuel vehicles can contribute to the fleet’s greenhouse gas emissions. The notice instructs manufacturers to assume these vehicles would use conventional gasoline 80 percent of their life and to calculate the greenhouse gas emissions starting in model year 2016. Manufacturers could alternatively submit real world data on flex-fuel vehicles to be used to create the weighting factor.