Both 911 engines comply with the stringent emission standards of Euro 5. Vehicles manufactured by Porsche demonstrate that even high-performance sportscars can achieve moderate emission values in their respective category. Indeed, not only is the 911 one of the most exciting cars around, it is also one of the cleanest.

This is achieved through the use of a two-stage cascade-type catalytic converter which comprises two monolith substrates on each of the twin exhaust tracts.

These specially coated substrates contain ultra-fine honeycomb channels in which pollutants are converted as exhaust gas passes through. The stereo lambda control circuitry controls and monitors each cylinder bank separately, while another lambda sensor on each cylinder bank monitors pollutant conversion in the respective catalytic converter.