Reducing emissions

    Reducing car emissions

    After NEFZ follows WLTP: A representative testing procedure for emissions in line with today’s requirements. No registration of new vehicles without compliance to this standard.

    After NEFZ follows WLTP: A representative testing procedure for emissions in line with today’s requirements. No registration of new vehicles without compliance to this standard.

    Consumption and emissions from combustion engines

    Gasoline and diesel engines burn fuel – usually gasoline, diesel, or natural gas. These fuels consist of different hydrocarbon chains, such that their combustion results in the end products of H₂O (water) and CO₂ (carbon dioxide). The carbon dioxide from exhausts is precisely measured and strictly limited by the European CO₂ fleet legislation, which measures CO₂ emissions on the basis of the NEDC (New European Driving Cycle). This was developed by the EU Commission to provide consumers and policymakers in Europe with a uniform benchmark. The NEDC has proven itself over many years as a harmonized, binding basis for comparing different vehicles or model generations. In addition to determining CO₂ emissions, the driving cycle also served to determine classic pollutant emissions and fuel consumption.

    The NEDC method previously used in Europe no longer met this requirement – it had been developed in the 1990s primarily for measuring pollutant emissions during a theoretical test drive. For this reason, the member states of the 98 UN/ECE Agreement (including all European countries, Japan, the USA, China, Russia, India and others) decided to develop a new test procedure under the umbrella of the UN/ECE that would cover the driving behavior of a vehicle in a globally representative manner – the WLTP (Worldwide Harmonized Light-Duty Vehicles Test Procedure). The automotive industry has played a key role in supporting and driving forward this initiative.

    WLTP: For strict adherence to exhaust limits

    The new WLTP is based on real driving data from a total of three continents (Asia, Europe, America) and twelve countries, making it significantly more representative. The test drives required for this comprised a total of 750,000 kilometers, which were carried out in metropolitan areas of emerging markets, such as India, as well as on highways in Europe and the USA.

    Certified WLTP measurements have been required for all newly registered passenger cars since September 1, 2018. Since September 1, 2019, this also applies to light commercial vehicles. This means that the fuel consumption, CO₂ and pollutant emissions of all vehicle types and variants are determined and documented using this new test procedure.

    Compliance with exhaust emission limits is a basic requirement for type approvals to be granted for new vehicles. Fuel consumption, together with the CO₂ value determined, represents a key criterion for the customer's purchase decision and is the basis for vehicle taxation in many countries. Even though the WLTP cannot reflect the entire range of actual vehicle use, it offers better information for car purchase decisions due to its more realistic results.

    In Germany, the Energy Consumption Labeling Ordinance regulates which consumption and emission values are binding for customer information. As of June 2021, however, this has not yet been updated to WLTP, such that car buyers are not yet informed of the more realistic consumption of new vehicles while manufacturers have to continue to use the outdated NEDC value. The VDA is campaigning for this energy consumption labeling regulation to be adapted as soon as possible so as to incorporate the information provided by the new WLTP.

    Alignment with vehicle tax

    Although customers are yet to be informed of the WLTP, it is already applied to the calculation of vehicle tax. Here, the Federal Ministry of Finance was quick to implement the changeover. Since the CO₂ values according to the WLTP test procedure are higher than those of the old NEDC standard, the rate based on the grams of CO₂ per kilometer should in fact be reduced by 20% for the German motor vehicle tax, since the WLTP is more realistic and leads to fuel consumption figures increasing by an average of around 20%. The failure to make this adjustment is tantamount to an increase of about 20% in the motor vehicle tax on new vehicles.

    Since the CO₂ fleet legislation was still developed on the basis of the old NEDC, the European Commission has decided not to adjust the CO₂ limit for new passenger car models, but rather to lower the CO2 emissions determined in WLTP in each case as if they were NEDC values. This is done using software called CO2MPAS, which was developed by the EU's Joint Research Centre (JRC). However, as these adjusted NEDC values are based on the stricter framework conditions of the WLTP test procedure, they will be slightly higher than the original test procedure. This results in an indirect tightening of the fleet regulation for manufacturers by around 6%.

    In the meantime, WLTP and (generally calculated) NEDC values are available for all newly registered vehicles. A CO₂ fleet value based on the new WLTP can therefore be determined for the first time for the 2020 calendar year. This is expected to happen before the end of summer 2021, and future CO₂ legislation for the years 2025 to 2030 can then be based on WLTP values. This will then finally mean the end of NEDC in Europe. However, there are still many other countries that continue to apply the NEDC, including North African countries and Australia. To be able to register vehicles in these markets, vehicle manufacturers must continue to measure the vehicles according to the NEDC.

    Department Powertrain & Emissions

    Dr. Jakob Seiler


    Read on