In order to meet the demands of EPA2010 standards， commercial vehicle manufacturers have evaluated various engine technologies that will provide low emissions and increased performance. SCR technology or Selective Catalytic Reduction is the option many engine and truck manufacturers have chosen. In simple terms， a fine mist of emission fluid is dosed into the exhaust that reacts and neutralizes the NOx molecules. A separate tank is fitted on the SCR truck to house the emission fluid. The rate of consumption for the fluid is 2 to 4% per gallon of diesel fuel. Manufacturers estimate that refueling the emissions tank will occur every other diesel fuel fill up.