Proposal to promote harmonisation in use of reference fuels for testing, including hydrogen fuel, based on the following justifications:

1. The use of test fuels is permitted for certification testing of gaseous and particulate pollutants and power/smoke testing in Europe. However, other countries that have adopted and referenced UN R85 may not allow this. In this case, manufacturers have to prepare fuels with different characteristics, which is costly and requires a long time due to the current inconsistent situation.
2. We believe that the use of test fuels for gaseous and particulate pollutant measurement tests should be a priority as a precondition for the introduction of more stringent emission levels.
3. Hydrogen fuelled vehicles are covered in UN Regulation No. 83, but hydrogen is not yet covered in UN R49 and UN R85.
4. Hydrogen fuelled engines could be one complementary option to reduce CO₂ emissions of future heavy-duty vehicles.
5. Therefore, hydrogen fuel should be integrated in UN R49 and UN R85 for better alignment with UN R83.

Proposal to allow higher tolerance for pressure measurement under paragraphs 4.7 and 4.8 (+ aligned intake and exhaust) in order to avoid refusal of test due to the non-compliance of pressure accuracy and based on the low impact on the αd. Value or approach (linearity?) to be discussed.

Background on changes proposed to UN R49 and UN R85 to address hydrogen fuel and heavy vehicles.

Proposal to permit the use of hydrogen (H2) as fuel for type approval of heavy-duty vehicles and to explicitly permit the usage of the reference fuel required for emission testing when the manufacturer applies for UN Regulations Nos. 24 and / or 49 type approval at same time.