Volkswagen: The scandal explained

[K. A. Pital]

Unless the others used defeat devices to conceal a 40x disparity... Sorry, but I say yes, look at Volkswagen.

[Beowulf]

Honda, Mitsubishi, Mercedes-Benz and Mazda have also fudged tests.

Mercedes-Benz’s diesel cars produced an average of 0.406g/km of NOx on the road, at least 2.2 times more than the official Euro 5 level and five times higher than the Euro 6 level. A spokesman for Mercedes-Benz said: “Since real-world driving conditions do not generally reflect those in the laboratory, the consumption figures may differ from the standardised figures.”
Honda’s diesel cars emitted 0.484g/km of NOx on average, between 2.6 and six times the official levels. A spokesman for Honda said: “Honda tests vehicles in accordance with European legislation.”
Mazda’s diesel cars had average NOx emissions of 0.293g/km in the real world, between 1.6 and 3.6 times the NEDC test levels. One Euro 6 model, the Mazda 6 2.2L 5DR, produced three times the official NOx emissions. A spokesman for Mazda said: “In compliance with the law, Mazda works hard to ensure that every petrol and diesel engine it makes fully complies with the regulations.”
Mitsubishi diesel cars produced an average of 0.274g/km of NOx, between 1.5 and 3.4 higher than in the lab. “The NEDC was never intended to represent real-world driving,” said a spokesman for Mitsubishi.

aka: "Quick, everybody hope they focus on Volkswagen only.

These look like it might be a matter of testing and reality diverging, which can happen for a variety of reasons, including differences in driver, and the testing cycle not quite matching the conditions found in real world driving. I mean, they train drivers to get the best numbers they can on the test.

[Borgholio]

Actually that appears to be a slightly different issue. Whereas VW programmed the car's computers to actively change performance variables when it detected a test was being performed, the other companies simply built and tuned their vehicles to pass the EU emissions tests while ignoring real world results. So it's actually technically legal what the other car companies did, since they didn't cheat. The just took advantage of a loophole in the system.

[Grumman]

The just took advantage of a loophole in the system.

It appears to be the opposite, actually. "Real-world driving conditions" are not constant even in a single location, let alone across the entire planet, which is why you use a standardised test instead of assuming that the traffic flow at the time and place you conduct the test is a representative sample of all traffic everywhere. And if completing that standardised test consistently produces less NOx emissions than day to day driving, that would not just produce unrealistically low test results - those unrealistically low test results would be the foundation for unrealistically low emissions standards.

[aerius]

These look like it might be a matter of testing and reality diverging, which can happen for a variety of reasons, including differences in driver, and the testing cycle not quite matching the conditions found in real world driving. I mean, they train drivers to get the best numbers they can on the test.

It is. It's very well known that EPA fuel economy tests are nothing like real world driving, so I suspected that the load cycles used for the NEDC tests are the same.

This is the NEDC cycle
https://en.wikipedia.org/wiki/New_Europ ... ving_Cycle

Note the slug like acceleration rates, seriously, who the hell takes 41 seconds to get up to 70km/h? Here's the science part. For diesel engines, NOx emissions are proportional to load, putting more load on the engine ups the combustion temperature which then produces more NOx. When a diesel is lightly loaded as it is on the NEDC cycle, the combustion temperature stays low which keeps the NOx emissions down, drive it hard and the temperature soars along with NOx emissions. You can try to get around that by running a richer fuel mixture, but then fuel economy goes down the drain and particulate emissions go sky high (ie. the diesel now belches a giant cloud of black smoke).

It ain't cheating, it's just the laws of science.

[Gaidin]

The just took advantage of a loophole in the system.

It appears to be the opposite, actually. "Real-world driving conditions" are not constant even in a single location, let alone across the entire planet, which is why you use a standardised test instead of assuming that the traffic flow at the time and place you conduct the test is a representative sample of all traffic everywhere. And if completing that standardised test consistently produces less NOx emissions than day to day driving, that would not just produce unrealistically low test results - those unrealistically low test results would be the foundation for unrealistically low emissions standards.

Literally the best you're going to get is multiple standardized tests for multiple conditions. And then that throws out its own wide range of results, each test with its own acceptable results. Fine. But you can't get around the need for a standardized test. Because real world conditions will literally change from day to day in a single location based on wather and of all things, and here's a shocker, traffic conditions.