Opel to be questioned over diesel emissions claims

Reports suggest some cars programmed to operate cleanly only within narrow parameters


Astra and Zafira diesels on Irish roads may be emitting around 11 times the legal limit of noxious nitrogen oxide, according to a German investigation of temperature-controlled exhaust manipulation.

Two of Opel's most popular 1.6 litre diesel models, examined by Der Spiegel magazine, have software that reportedly switches off filtering above 33 degrees and below 20 degrees.

Opel has conceded its diesel filtering worked fully only "in the area of 20 to 30 degrees". Given Met Éireann data, with highest average temperatures of 18 to 20 degrees, Opel Astras and Zafiras on Irish roads are polluting well above legal limits for much of the year.


Volkswagen scandal

Months after the Volkswagen manipulation scandal, executives at Opel, a German subsidiary of General


, have been ordered into Berlin’s federal transport ministry this week to explain the claims.

VW diesels were programmed to manipulate emissions, running more cleanly when wheels moved with an immobile steering wheel. Opel insists its cars do not run software that detect a test situation. However, Der Spiegel suggests Opel cars are programmed to operate cleanly only within narrow, predefined parameters.


German computer programmer

Felix Domke

, who has studied Opel software, said full emissions filtering takes place only between 17 and 33 degrees, below 145km/h or 2,400rpm.

Car emissions tests regulations prescribe test temperatures between 20 and 30 degrees, a maximum speed of 120 km/h and 2,200rpm.

According to Germany’s DUH environment lobby group, the Zafira motor operates just 20 per cent of the time in its “clean” AdBlue mode.

Opel, which declined to provide data for Der Spiegel's tests, said the "isolated findings of a hacker do not reflect the complex interplay of a modern emissions filtering system".

Derek Scally

Derek Scally

Derek Scally is an Irish Times journalist based in Berlin