Emissions performance of Euro VI-D buses and recommendations for Euro 7 standards

The proposed Euro 7 standards, which are to be implemented in 2027, set lower emissions limits than the current regulation, Euro VI, while expanding the driving conditions that are evaluated. This study provides insight into the emissions performance of the latest generation of diesel buses in Europe. The ICCT collaborated with VTT Technical Research Centre of Finland Ltd (VTT) to perform a series of on-road measurements on two buses type-approved to the Euro VI-D standard over various duty cycles. This working paper is a summary of the key findings. The analysis found that both buses exhibited emissions performance generally in accordance with the Euro VI-D type-approval requirements. However, the NOx emissions over the highest emitting test windows were three to five times higher than the proposed Euro 7 cold limit. NOx emissions in hot operation ranged between one and four times the proposed Euro 7 cold limit. NOx emissions in hot operation ranged between one and four times the proposed Euro 7 hot limit.