Volkswagen Diesel Cars Use Up To 14% More Fuel After Software “Fix,” With NOx Emissions Still 400% Higher Than Lab Figures, Study Shows

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I often hear the claim that diesel cars are of value owing to their reportedly higher fuel-economy than gas/petrol powered cars. The thing about that claim, though, is that it’s only true when diesel cars are allowed to release illegally (in many regions) high levels of dangerous pollutants.

In other words, the superior fuel-economy of diesel cars is dependent upon “superior” pollutant releasing performance — the two outcomes being linked together. When diesel cars are made to meet common emissions standards they end up with a far lower fuel-efficiency, in other words.

A new analysis from the Australian Automobile Association (AAA) has (again) confirmed as much — with Volkswagen diesel cars being found to use up to 14% more fuel after being recalled and “fixed” than previously. Notably, even after the software fix in the vehicles in question was implemented, NOx emissions were still over 400% higher than the levels seen in lab testing (official figures, that is).

A press release on the matter provides more:

“Conducted in partnership with the Fédération Internationale de l’Automobile (FIA), the real world testing was commissioned to quantify performance changes associated with the software upgrades being implemented on affected vehicles.

“In late 2016, AAA commissioned research firm ABMARC to run two tests on an affected VW vehicle — one before recall and one immediately after. The test result indicates that a 2010 model Euro 5 VW Golf used an average of 7% more fuel — or 0.5 liters/100km — after it had the recall completed. This ranged from using 2% more fuel while driving in urban areas, 7% more fuel on rural roads and 14% while driving on highways.

“The tests showed a reduction in emissions of oxides of nitrogen, carbon monoxide, and particulate matter occurred after the recall fix. However, the NOx emissions were still 4.11 times the laboratory limit after the recall when tested under real driving conditions.”

In other words, the “fix” instituted by Volkswagen to reduce emissions to legal levels essentially undid the supposed large fuel-economy superiority of its diesel cars, as compared to gas/petrol cars.

Continuing: “The testing also indicated that both power and torque had increased slightly after the recall fix. The testing further supports the AAA’s call for a real-world emission testing program in Australia. The AAA has strongly advocated for the introduction of a real-world emissions test program following its own research program, which tested 30 Australian cars, on Australian roads, using Australian fuels.”

It’s hard to argue with the need for real-world testing — if actual real-world repercussions stemming from illegally high emissions levels actually mean anything to anyone, that is.

With regard to the real-world testing discussed just above, those wanting to read about that can do so here.