Even new diesels pollute the air considerably – and do not help with climate protection

The real nitrogen oxide emissions of Euro 6 diesel cars are significantly above the Euro 6 limit. Source: Stefan Redel / Fotolia.com |
Diesel cars that meet the current Euro 6 European emission standard emit – under real operating conditions on the road – six times more harmful nitrogen oxide than permitted. This is the sad conclusion of a recent analysis of car exhaust emission measurements carried out on behalf of the German Environment Agency. The fact that emissions on the road are so much higher than during type approval testing is significantly due to the unrealistic laboratory testing conditions: Chassis dynamometers are operated at temperatures between 20 and 30 degree Celsius while average German temperatures are much lower. The exhaust after-treatment system often does not work sufficiently outside test conditions and nitrogen oxide (NOx) emissions increase sharply.
UBA's President Maria Krautzberger says: "We must have clean air in cities. It is very clear that the automotive industry must assume responsibility and deliver a solution which consumers can live with." The European Union has already responded: from September 2017, new vehicle types will also be tested for approval based on the RDE (Real Driving Emission) method in addition to the laboratory tests. The RDE method measures emissions during driving on the road. The purpose is to ensure that exhaust after-treatment works under many operating conditions and only little NOx is emitted.
Initially nitrogen emissions of vehicles may exceed the “laboratory limit” of 80 milligrams per kilometer during RDE-testing: 110 % (up to 168 mg / km) exceedance will be allowed, and from January 2020 50 % (up to 120 mg / km) is still legal due to measurement uncertainties. Current legislation for total emitted particle number of new diesel and gasoline (direct injection) vehicle types limits the excess during RDE-testing straight to 50 % starting September 2017.
From UBA’s perspective, the subsidization of diesel fuel has to be put on trial, too. In the passenger car sector subsidies sum up to EUR 3.5 billion for the German taxpayer. Even with the deduction of higher annual car taxes for diesel cars (compared to gasoline vehicles), diesel car owners are exempted from roughly 1.5 billion euros in tax per year. Even though Euro-6 diesel cars emit roughly 25 times more NOx than modern gasoline models. The argument that the subsidization of diesel vehicles is for the benefit of climate protection also does not stand up: in 2015 the CO2 emissions of newly registered diesel cars were on a par with those of newly registered gasoline-fueled cars, both standing at 130 grams per kilometer. In theory, diesel cars do have an advantage of 15 % in CO2 emission compared to gasoline cars equipped with the same power output. However, this benefit gets eaten up as it is compensated by the introduction of the fuel-guzzling SUV concept and oversized engines on German roads. A zero-sum game for the climate.