Might there be many legitimate reasons why the emissions vs performance tradeoff might be tailored to driving conditions? Of course when the car is idling it would make sense to minimize emissions as much as possible, just as an idle CPU can utilize a lowered clock speed.
That isn't to say that the CEO is at fault, nor would it be expected that the CEO of an enormous company with thousands of engineers would know about or direct specific engineering decisions (and in fact he denies that he knew). More likely than not, he issued unrealistic directives to the engineering team, who met the demands in the only way they could at the time. That doesn't make it right by any stretch, but that appears to be what happened.
It depends on how the emissions are measured. They could be measured per RPM, per mile, per gallon, per pound transported, or by any of those over time, or some basket of utilization patterns modeled after real-world use.
If you slam the accelerator to the floor, the vehicle produces more emissions than if you'd continued along at a steady pace. Emissions control is a combination of active and passive systems, along with careful moderation of inputs to the engine. So it seems plausible that a complex, computer-controlled vehicle would optimize emissions vs performance by modifying many of the available variables in response to driving conditions.
That is certainly a good point. However in this case, the specifics of what they were doing obviously crossed the line. Normally I roll my eyes when I hear about EPA issues, given that agency's penchant for making mountains out of molehills and ravenous appetite for horrendous fines. But in this case, many rational, scientifically credible people all seem to agree that they were intentionally and egregiously violating the law.
That does seem to be the case. I'm curious when the dust settles if the spirit or the letter (or neither, both) of the EPA requirement was violated.
Here is the explanation for what VW is accused of doing.
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Specifically, VW manufactured and installed software in the electronic control module (ECM) of these vehicles that sensed when the vehicle was being tested for compliance with EPA emission standards. For ease of reference, the EPA is called this the "switch". The "switch" senses whether the vehicle is being tested or not based on various inputs including the position of the steering wheel, vehicle speed, the duration of the engine's operation, and barometric pressure. These inputs precisely track the parameters of the federal test procedure used for emission testing for EPA certification purposes. During EPA emission testing, the vehicles' ECM ran software which produced compliant emission results under an ECM calibration that VW referred to as the "dyno calibration" (referring to the equipment used in emissions tested, called a dynamometer). At all other times during normal vehicle operation, the "switch" was activated and the vehicle ECM software ran a separate "road calibration" which reduced the effectiveness of the emission control system (specifically the selective catalytic reduction or the lean NOx trap). As a result, emissions of NOx increased by a factor of 10 to 40 times above the EPA complian levels, depending on the type of drive cycles (e.g., city, highway).
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And here is what happened when this was found out and the EPA and CARB tried to find out what was happening:
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VW continued to assert to CARB and the EPA that the increased emissions from these vehicles could be attributed to various technical issues and unexpected in-use conditions. VW issued a voluntary recall in December 2014 to address the issue. CARB, in coordination with the EPA, conducted follow up testing of those vehicles both in the laboratory and during normal road operation to confirm the efficacy of the recall. When the teting showed only a limited benefit to the recall, CARB broadened the testing to pinpoint the exact technical nature of the vehicles' poor performance, and to investigate why the vehicles' onboard diagnostic system was not detecting the increase emissions. None of the potential technical issues suggested by VW explained the higher test results consistently confirmed during CARB's testing. It became clear that CARB and the EPA would not approve certificates of conformity for VW's 2016 model year diesel vehicles until VW could adequately explain the anomalous emissions and ensure the agencies that the 2016 model year vehicles would not have similar issues. Only then did VW admit it had designed and installed a defeat device in these vehicles in the form of a sophisticated software algorithm that detected when a vehicle was undergoing emissions testing.
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Is there any information about how this happened organizationally within VW? Was there widespread awareness?
For instance, suppose the vehicle was programmed to shut off its engine when stopped at a stoplight. Suppose the test scenario measures emissions while stopped at a stoplight...
The engine shutoff feature is irrelevant, as it happens in the wild when not running emissions tests.
Varying emissions based on load is perfectly reasonable.
I saw this reported, but also saw that it actually just looks for acceleration and steering conditions often found in testing scenarios. There was no mention of whether these conditions are also found in routine use of the vehicle. Not sure which is true.