How Volkswagen gamed the emissions tests for its diesel vehicles

Three experts chime in on how VW circumvented emissions tests

2014 volkswagen golf tdi feb 2014
Credit: Image: Volkswagen

In case you haven’t noticed, modern cars are essentially high-end computers with an engine, some shiny metal parts and four wheels.

The “interface” you see for controlling the radio and climate is becoming more and more like a huge iPad in the center of the dashboard. The blindspot detection systems, adaptive cruise control and collision warnings all use complex software algorithms. And, as we have learned recently about emissions testing, there is software that controls how many pollutants spill out of the exhaust system.

Recently, Volkswagen came under fire in the U.S. for “gaming” the emissions tests conducted by the EPA. Three independent analysts told me how this worked, and it’s rather ingenious. It turns out the laws for emissions testing themselves may have played a role as a way to avoid being flagged as "dirty" diesels.

As analyst Rob Enderle explained to me today, the law specifically states that the emissions must pass “at the time of testing,” which is intended as a way to enforce compliance. It's supposed to be a spot check. Yet, it’s this very condition that triggered the software VW used to game the system. “At the time of the test” is when the software kicks in to control the emissions. When the test concludes, the software then goes back to “normal” mode. The diesel versions of cars like the Passat and Jetta then seem sporty and clean.

Charles King, an IT analyst who studies infrastructure and data centers and who blogs at Computerworld, gave me a similar explanation. He says it’s likely the car connected over a secure link to the Department of Motor Vehicles (DMV) for the state where the tests were conducted. That’s the irony — this connection is what triggered the software change to make the car seem like it was controlling emissions.

Ken Westin, senior security analyst at Tripwire, further explained to me that the emissions tests are controlled by the OBDII port located just beneath the steering wheel on all new cars made after 1998. “Computers can be programmed to lie,” he says, explaining how the car would only temporarily control the emissions to pass the test, then go back to running at a higher performance level. Indeed, in my own tests of diesel-powered cars in the VW and Audi line over the past few years, they always seemed unusually sporty and responsive. It seemed like you had the best of both worlds. This is where the term "turbo diesel" comes from, which we now understand as a misnomer.

Enderle said other automakers may have pulled similar tricks to circumvent emissions testing. “If it is a problem with the law and the emissions system hurts performance and we have other compliant high-performance diesel cars then it seems likely other engineers have done similar things,” he says.

According to Enderle, this is not the first time automakers have tried to evade the EPA testing laws. Trucks were programmed to run “clean” but over time would slowly shut off emission controls as a way to increase gas mileage.

In recent years, other automakers like Hyundai and Kia have come under scrutiny for claiming a higher MPG rating in their cars. This adds to all of the recalls, airbag issues and other problems that are plaguing the industry right and left. For now, all we can do is wait and see if VW corrects the software and rebuilds trust. The really troubling part? It seems as though this might be just the beginning of cars doing software tricks.

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