Summarizes provisions of the implementing act adopted in May 2017 by the European Union for type-approval of CO2 emissions and fuel consumption of on-road heavy-duty vehicles, which will go into effect in 2019 and 2020. On May 11, 2017, during the 67th meeting of the Technical Committee—Motor Vehicles, member states of the European Union unanimously adopted a draft implementing act put forward by the European Commission on the certification of the CO2 emissions and fuel consumption of heavy-duty vehicles. Starting January 1, 2019, heavy-duty vehicles belonging to one of the four vehicle groups with the highest contribution to on-road freight carbon emissions will be certified for their CO2 emissions and fuel consumption. Six additional heavy-duty vehicle groups will be required to be certified for CO2 emissions and fuel consumption by January 1, 2020. The certification procedure is based on a vehicle simulation tool that uses as inputs the measured performance of the different vehicle components.