Three engines in the John Deere Power Systems lineup of off-highway diesel engines in the 75 to 174 hp range have been certified as compliant with Interim Tier 4 EPA standards as well as European Union Stage III B and California Air Resources Board regulations. The PowerTech PWX 4.5L (pictured) and PVX 4.5L engines and the Power Tech PVX 6.8 join the previously certified engines above 174 hp. JDPS engines met the regulations with cooled-exhaust gas recirculation for NOx control, adding an exhaust filter for reducing particulate matter. The engines feature full-authority electronic controls, a 4-valve cylinder head, a high-pressure fuel system, wastegate or variable-geometry turbocharging and an air-to-air aftercooling system.