New ICCT study finds CO2, NOx emissions of Euro 6 diesel and gasoline cars under real-world settings exceeding limits
A new study commissioned by the International Council on Clean Transportation (ICCT) investigates the real-world emissions of four Euro 6 passenger cars—one gasoline and three diesel vehicles with different aftertreatment technologies—tested under variable conditions. The investigation was conducted by the Laboratory of Applied Thermodynamics, of the Aristotle University of Thessaloniki, and its spin-off company, Emisia.
The investigation found that every tested vehicle exceeded its CO2 certification levels in a range varying from 21% to 37% under the laboratory type-approval test using real-word road-load settings. Two of the three diesel vehicles exceeded the NOx limit by 19% and 66% while tested under the laboratory type-approval test. Under RDE-compliant on-road trips, using PEMS emission measurements, NOx emissions from diesel vehicles showed average levels varying from 5 to 16 times the Euro 6 limit.
NOx emissions of diesel vehicles driven in more dynamic driving conditions increased further to reach a range from 26 to 40 times the Euro 6 limit. NOx and carbon monoxide (CO) emissions from the gasoline vehicle remained below the Euro 6 limit under any of the laboratory tests and RDE-compliant trips. While tested in more dynamic on-road conditions, emissions exceeded the laboratory type-approval limit by a factor of 2.5 for NOx and by a factor of 2.4 for CO.
|NOx emissions under laboratory and on-road tests. Source: The ICCT. Click to enlarge.|
The four vehicles in the test were:
- Vehicle 1 (LNT): BMW 520d 2.0
- Vehicle 2 (LNT): Nissan Pulsar 1.5dCi
- Vehicle 3 (SCR): Opel Insignia 2.0 CDTI
- Vehicle 4 (GDI): VW Polo 1.2TSI
The laboratory testing reiterated the NEDC type-approval test using two different estimation of on-road frictions for the different vehicles (road-load settings). The first used the car manufacturer’s original parameters, and the second our own independent measurements. Another series of tests completed the laboratory investigation and measured emissions on different vehicle speed profile (i.e., ARTEMIS, WLTC) at ambient conditions varying from 18 °C to 25 °C.The four vehicles were tested on the road following the RDE regulation protocol, which includes defined limits for dynamic driving conditions (e.g., exclusion based on vehicle’s speed and acceleration, and cumulative positive altitude). For the last series of on-road tests, the four vehicles were driven more dynamically on a hilly road to investigate emission levels outside the scope covered by the regulation.