Comparison of real-world off-cycle NOx emissions control in Euro IV, V, and VI

Heavy-duty vehicles built and certified in conformity to Euro IV and V emissions standards frequently do not achieve the real-world NOX emissions expected under those standards. Now data is becoming available to show whether new certification protocols in the Euro VI regulation resolve this problem. The evidence thus far indicates that under Euro VI, NOX emissions are indeed meeting expectations, even in the most difficult operating conditions. As a result, Euro VI standards may achieve a much greater reduction in NOX emissions from Euro IV/V levels than the emissions limits alone would indicate.