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DUH: Opel Zafira diesel shows emission testing irregularities

24 October 2015

Deutsche Umwelthilfe (Environmental Action Germany, DUH) released results of emission testing of an Opel Zafira 1.6 CDTI diesel, where NOx emission levels from the vehicle were found to depend on whether the rear wheels of the vehicle were turning during the test or not. If confirmed, these results would suggest that the vehicle might be equipped with two calibrations: one for regulatory testing (where normally only the front, driving wheels are turning) and one for road driving (when all wheels are turning).

The tests were conducted at the Bern University of Applied Sciences in Switzerland. The vehicle was a Euro 6b Opel Zafira 1.6 CDTi with a mileage of 6,000 km. The vehicle is equipped with a DPF and urea-SCR aftertreatment.

The vehicle was tested on a chassis dynamometer over the regulatory NEDC test cycle using two test modes: (1) a two-wheel drive (2WD) mode, where only the front, driving wheels were turning, and (2) a four-wheel drive (4WD) mode, with all wheels turning. The 2WD mode represents the official regulatory test procedure.

In the 2WD mode, NOx emissions ranged from about 45 to 78 mg/km, in all cases below the Euro 6 limit of 80 mg/km. In the 4WD tests, however, NOx levels ranged from 157 to 317 mg/km, significantly exceeding the Euro 6 limit. These results suggest that the vehicle was equipped with a dual engine calibration designed to defeat regulatory emission tests, similar to the emission strategy implemented in a number of vehicles by Volkswagen.

DUH submitted the testing results to Kraftfahrt Bundesamt (KBA), the German authority responsible for vehicle type approval testing, with a request to re-test the Opel Zafira vehicle.

In response to the DUH report, Opel conducted an emission test on a Zafira with a 1.6-liter diesel engine on a four-roller test bench with all wheels in motion. The test, conduced in the presence of TÜV Hessen, found that emissions from the Zafira vehicle tested by Opel were within the legal limits. “It remains valid for all of our cars and without exception: GM-developed software has no features that detect whether the vehicle is undergoing an exhaust emissions test,” said Opel in a statement.

Source: DUH