[henningo]

I think it is a bit unfair to just blame the manufacturers. The legislation could likely be changed to make for a more robust test approach. After all, it is engineers we are talking about here, if they are given a task to optimize an engine's emissions and fuel consumption to a specific drive cycle they will do it. But then of course you have the ethical aspects which I won't go into.

A computer science analogy to this would be if I gave you an uncompressed image and you had to develop a compression algorithm that made the image as small as possible, you could likely come up with a really good solution. But your algorithm most likely wouldn't do as well on any other image.

I think that a feasible solution to this will be to test under a wider range of conditions and add (statistically defined) noise to the testing procedures. The added cost of additional testing would be very small in comparison to the cost of a vehicle development program.

A good overview of the different drive cycles can be found here: http://www.car-engineer.com/the-different-driving-cycles/

[ucsdrake]

"A computer science analogy to this would be if I gave you an uncompressed image and you had to develop a compression algorithm that made the image as small as possible, you could likely come up with a really good solution. But your algorithm most likely wouldn't do as well on any other image."

That analogy doesn't hold. It's more akin to developing two compression algorithms, one for the general case, and a specific algorithm which is used only when your image is detected for better than the general compression performance use case.

It is entirely fair to blame the manufacturers for this. Gaming emissions results required effort to accomplish, and is completely unethical from an engineering standpoint.

[henningo]

I agree that the analogy doesn't hold for the recent VW debacle (where the calibration was changed during certification testing), but it holds for the industry in large and what has been going on for the past 10-20 years, which is what the paper is about.

The vehicle manufacturers optimize the engine calibration to the drive cycle they are trying to beat. That is why a US-spec BMW has a different engine tune than a Euro-spec BMW for example, the drive cycles are different.