How a Professor Uncovered the VW Diesel Scandal and Changed Diesel Forever

How a Professor Uncovered the VW Diesel Scandal and Changed Diesel Forever

Dr. Arvind Thiruvengadam, research assistant professor at West Virginia University is the man who uncovered Volkswagen’s diesel-emissions scandal. But according to him, this German firm is not the only automaker that’s missing the mark.

VW Diesel Emissions

During a presentation and Michigan State University, Thiruvengadam explained that manufacturers don’t always maintain emissions numbers that are close to certification levels because of wildly variable real-world conditions, be it differences in fuel quality, disparate driver habits and ever-changing road conditions. All of these things impact what comes out of your car or truck’s tailpipe.

However, Thiruvengadam explained that anywhere from two to five times the legal emissions limit is normal in certain driving situations. “We don’t raise eyebrows on that kind of deviation,” he said.

In comparison, Volkswagen’s diesels were literally off the charts. “We are looking at 35 to 40 times deviation,” noted Thiruvengadam, figures that are indicative of severe and deliberate manipulation.


If anyone was going to uncover this scandal, it was Thiruvengadam. Much of his professional career has been dedicated to studying internal-combustion byproducts, which is exactly what he’s done at West Virginia University’s Center for Alternative Fuels, Engines and Emissions, CAFEE for short.

This non-profit research organization evaluates vehicle after-treatment systems, new engine technologies and, of course, extensively tests existing and future fuels. Thiruvengadam said he focuses largely on quantifying real-world emissions from heavy-duty trucks. “Very rarely [do] we get into light-duty work,” he said, since compression-ignition engines are relatively still rare in U.S. passenger cars. But when Volkswagen’s so-called clean-diesel technology reached the market five or six years ago it was, naturally, “of great academic interest to us,” he said.

More Than One Way to Skin a Cat

There are essentially two ways to make a diesel engine meet today’s emissions regulations, either with a lean nitrogen-oxide (NOx) trap or selective catalyst reduction (SCR). The latter is extremely prevalent in the market, using urea as a reductant to eliminate nasty emissions. The former is technology VW installed in some of its smaller diesel-powered cars.

SEE ALSO: How VW Needs to Fix Its Reputation: The Skinny with Craig Cole

Accordingly, “The Jetta was a no-brainer [to test],” said Thiruvengadam, since Volkswagen claimed it could meet U.S. emissions standards without a more complex and expensive SCR system.

To prove the efficacy of this automaker’s technology, Thiruvengadam and colleagues tested several vehicles on an extensive 4,000-mile road trip from Los Angeles to Seattle, gathering a mountain of solid data along the way. They chose this route because of how varied it was. There were congested cities to navigate and mountains to climb, desert heat to cope with along with different atmospheric conditions.

They wanted to avoid strictly highway driving, which is “a sweet spot for most engines,” explained Thiruvengadam. Steady-state motoring is beneficial for fuel efficiency and emissions, being “very conducive for these after-treatment systems to be working.”

Overall, they evaluated a Volkswagen Passat and BMW X5, both of which were equipped with SCR emissions-control technology, plus the aforementioned Jetta. During the drives, each vehicle was literally overflowing with bulky test equipment that made them less than enjoyable to be in for hours on end, but any discomfort was offset by a voluminous quantity of quality numbers.


Thiruvengadam explained that the nature of their research was purely academic. “The hypothesis was not that we were going to go after manufacturers,” he said. They wanted to figure out how these different emissions-control systems performed in the real world.

Caught Red Black Handed

And that data revealed some stunning revelations, primarily that Volkswagen was cheating in a big way. But even at first, Thiruvengadam and his colleagues couldn’t believe what they were seeing.

“We really did not immediately focus on a defeat device,” he said, even though that’s ultimately where the data led. And that term is something of a misnomer. Thiruvengadam noted that, “Although it is called a device … there is never really a ‘device’ in play.” Instead, this refers to special code in the vehicle’s powertrain-control computer that alters how the engine performs. In the case of certain Volkswagen models, it reduces tailpipe emissions when it senses the vehicle is undergoing a test.

ALSO SEE: How Come Other Automaker’s Diesels Can Meet US Emissions Standards?

There are numerous input signals an engine’s computer can use to tell if emissions are being evaluated. For instance, Thiruvengadam said if the rear wheels are not spinning the car can probably tell if it’s on a chassis dynamometer. Disabled traction control or an open hood can also signal that something out of the ordinary is going on.

Why Cheat?

But why would Volkswagen make such a colossal blunder, deliberately and blatantly violating the law? “At this point we can only speculate what the motives were,” said Thiruvengadam. “But the widespread theory why a manufacturer would go down that path is [to improve] fuel economy.”

In spite of this, Thiruvengadam said he doesn’t think VW cheated in the name of better efficiency. He speculates cost was the driver, noting that with SCR emissions-control systems diesel engines can have up to five different catalysts. Naturally, this gets expensive very quickly.

VW may have cheated to save money but in the long run they’ve done untold damage to their reputation, plus squandered billions of dollars, to say nothing of customer goodwill.

Is There a Viable Fix?

It’s obvious that VW has put itself in a bad situation and the one question on everyone’s mind is can their defective vehicles ever be repaired? According to Thiruvengadam, “The software fix is the easiest fix for them.” However, if the lean NOx traps are undersized they can never be made to properly meet regulations.


Theoretically, affected cars could be retrofitted with SCR emissions-control technology, but this entails adding new catalysts, computers and software, extra wiring, a urea tank and more. “The easier solution is to just buy back the cars,” said Thiruvengadam.

VW’s emissions scandal is a textbook example of what NOT to do. Other companies should pay careful attention going forward. Still, if there’s any good news for this German automaker Thiruvengadam said, “[They’re probably] just happy it was found by a university and not a rival automaker.” Imagine how ugly things could have gotten if Mercedes-Benz or General Motors uncovered their little secret.

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  • Ed

    This supposedly cancelled ad explainer is making the rounds..

    Dr. Thiruvengadam: Since our emission standards were created to only cover CO, CO2, NOX and particulates, does using urea to reduce NOX introduce anything else into tailpipe emissions that is harmful but not regulated?

  • craigcole

    LOLOLOLOL!!! Love the line, “Blue die (sic) added to for enhanced marketing.”