Working Paper

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

Vehicle testing

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 hot limit.

One of the buses tested exhibited ammonia emissions performance 40% below the proposed Euro 7 limit, while the other bus exhibited emissions 40% above it. Nitrous oxide emissions contributed 7% to 9% of the greenhouse gas emissions of the buses tested. The proposed Euro 7 limits for these emissions are close to the reductions can be achieved with current emissions control technologies.

The particulate number requirements under Euro 7 would demand higher filtration efficiency than what current technologies offer. The number of particles in the 10 to 23 nm size range, which would also now be regulated under Euro 7, is substantial and would increase the PN count between 60% and 100%.

An in depth analysis of post-processing methods on heavy duty Euro VI exhaust emissions_2nd_revision_