Mercedes-Benz pulled into Dieselgate

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Words: Nile Bijoux
13 Jun 2018

Despite following the age-old advice of the unfaithful, “deny-deny-deny” hasn’t paid off for Mercedes-Benz. Nearly 240,000 diesel-powered Merc’s will be recalled after five pieces of emissions-cheating software were discovered.

The German Transport Ministry (KBA) ordered the recall yesterday after finding the illegal software in 774,000 engines across Europe.

“The Government will order 238,000 Daimler vehicles to be immediately recalled Germany-wide because of unauthorised shutoff devices,” the KBA said in a statement.

The agency said the worst affected models were the C-Class 220d sedan and wagon, the Vito van and the GLC 220d coupe SUV.

Last month, Daimler was ordered to recall a separate 4923 Vito vans that had been sold despite not meeting the correct compliance, and it “voluntarily” recalled three million cars to improve emissions performance.

The cheater software is the ‘Thermal Switch’, used by Daimler, Opel, PSA and others to exploit a “system longevity” loophole in nitrogen oxide (NOx) testing. In Mercedes-Benz applications, the cars switch off their emissions controls below nine degrees and above 26 degrees to guarantee the systems survive for the vehicle’s lifespan.

Despite the KBA’s findings, Daimler still intends to fight, saying “Open legal questions will be clarified in the objection proceedings.”

Back in 2016, six Mercedes-Benz models appeared in environmental lobby group Transport and Environment’s ‘Dirty 50’ list of diesel-powered passenger vehicles.

“Regulatory limits for NOx emissions are also breached by a significant margin when tested in conditions even slightly divergent from those prescribed in the EU test protocol (NEDC),” the group said. “The principal reason for such gross exceedances (sic) is that carmakers routinely switch-off technologies that clean up the exhaust when the car is driven on the road, and only operate these fully during the narrow conditions of the tests.

“This is partially to improve official fuel economy figures but is also due to questions about the durability of the emissions treatment systems carmakers have used – specifically exhaust gas recirculation systems that pump hot exhaust gases with a lower oxygen content back into the cylinders to lower production of NOx.”

The survey put MB’s average diesel fleet emissions at a rather astounding 6.4 times the EU’s NOx limits, worse than Ford, Kia, Toyota, Honda, Audi, Mazda and Jaguar Land Rover.

BMW and, surprisingly, Volkswagen were the best at real-world emissions, emitting around twice the legal limit in the real world.

Bear in mind, the survey results were released a couple of years ago. Mercedes says its new-from-2017 3.0-litre straight-six diesel engines don’t need a thermal switch by moving the NOx catalysts closer to the exhaust manifold.



NZ Autocar

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