Fueled by compressed natural gas, liquefied natural gas, or renewable natural gas, 6.7 liter ISB6.7 G Natural Gas Engine utilizes Cummins Westport's proprietary spark-ignited, stoichiometric combustion with cooled Exhaust Gas Recirculation technology. Three-Way Catalyst aftertreatment is packaged as muffler, and is maintenance-free, eliminating need for DPF or SCR aftertreatment. Available up to 260 hp with 660 lb-ft of torque, MidRange engine offers automatic transmission capability.