Comparing Real-world Off-cycle NOx Emissions Control in Euro IV, V, and VI

Heavy-duty vehicles conforming to Euro IV and V standards frequently show poor real-world NOx emissions performance. Evidence indicates that new certification protocols in Euro VI resolve this problem, and Euro VI-compliant heavy-duty vehicle NOx emissions meet expectations. Although the results indicate that Euro VI standards are working effectively, these standards must still be complemented with in-use compliance and enforcement programs to ensure a successful and well-rounded approach to heavy-duty vehicle emissions control.