GM under renewed #dieselgate suspicions

Opel-Vauxhall-Vectra Picture courtesy xtuners.com

Where will the next dieselgate shoe drop? Informed observers are convinced it will be at GM. This weekend, the London Times published tests that show Vauxhall’s Corsa, Astra and Vectra diesel cars as “among the most polluting models on Britain’s roads — typically emitting twice the level of toxic nitrogen oxides (NOx) seen from rival manufacturers’ cars.”

According to the report, the Vauxhall Insignia “emits 10 times more NOx than allowed under EU law, making it perhaps Britain’s most polluting car from any mainstream manufacturer.” Vauxhall cars are rebadged Opels, made by GM’s permanently troubled European subsidiary.

The tests were performed by Leeds University, using a revolutionary roadside emissions system that analyzes the exhaust plumes as cars drive by. The system allows a rapid compilation of a database. For the study, the University analyzed exhaust emissions from “tens of thousands of cars, including 1,652 Vauxhalls.”

GM’s Opel-Vauxhall cars appear to be polluting more as regulations become more stringent.  Said James Tate, who led the study at Leeds:

“While almost all models produce more NOx than allowed under EU limits, most have managed to reduce this, or at least stay flat. Vauxhall’s models, by contrast, have produced increasing amounts of NOx just as the legal limits have been getting tighter.”

Tate found that new Corsas emit 50 percent more NOx than their predecessors. The Astra’s emissions more than doubled in the new model. The Vectra’s NOx output was found 2.7 times higher than before – and ten times over the current Euro 5 limit.  How could cars that bad pass EU tests? The University suspects VW-like cheating. Says Tate:

“I suspect Vauxhall’s pollution reduction systems operate well at low loads, like those used in emissions test laboratories, but cut out at higher loadings. They can pass the emissions test, but pour out NOx in normal driving.”

The revelations come after the Bern University of Applied Sciences published dyno tests with Opel cars that raised a strong suspicion of defeat devices under the hood. Opel strongly denied the allegations, saying that the GM-developed software in its cars does “not contain any features that can detect whether the vehicle is being subjected to an emission test.”

GM itself has demonstrated that there are other ways to cheat than figuring out that the car is on the dyno. Decades ago, Cadillac had to recall 500,000 cars with a computer that injected more fuel into the engine whenever the A/C was on. When it did so, the catalytic converter could not cope with the carbon monoxide, which was spewed into the air. Technically, no defeat device. However, cars usually are driven with the A/C on, but tested with the A/C off. There is talk in German automotive circles that something similar might be going on in Opels.