skip to content
Driving Line Mark Logo

The Real Reason VW Got Caught: Behind The Scenes of The Dieselgate Scandal

It was the scandal that rocked the automotive world. It was Dieselgate and it forced the world’s largest automaker, Volkswagen, to pay out more than $20 billion in civil penalties in the U.S. alone. The scandal cost VW its long-standing credibility in the world of diesel cars (of which it no longer produces) and still has curious minds pondering just how far back its emissions-skirting policies actually stretch. It took mobile emissions testing rather than standardized, run-of-the-mill chassis dyno evaluations to catch on to VW’s deceit—and it was pulled off by three graduate students and the director of emissions research at West Virginia University, who were working off a measly $70,000 grant.

Volkswagen Dieselgate Scandal

Volkswagen has since recovered and made a successful pivot toward electric vehicles, but the scandal proved near-fatal for diesel-propelled passenger vehicles the world over. We’ll go over how VW was caught below, but also pull back the veil to explore the most plausible reasons behind its decision to trick regulators, its customers and the general public with its “clean diesel” 2.0L and 3.0L TDI engines.

Why Would An Automaker Want To Cheat?

TDI Volkswagen Passat Diesel

There are multiple reasons behind Volkswagen’s top-down decision to lie about its engine’s emissions compliance. Some reasons build upon others. Case in point, curbing NOx (nitrogen oxide) emissions can come at the expense of fuel economy, as well as emissions equipment longevity and overall engine durability. Simply put, the engine’s intended efficiency is hampered with NOx emissions-control devices (namely exhaust gas recirculation) onboard. Couple the reliability issues and performance hindrances that often arise from using NOx-fighting components with the automaker’s need to preserve the reliability of its cars and ensure that they live up to the mileage and longevity hype and you get a perfect storm—which also happens to be the color green.

Additional Reasons For Deceit

AdBlue Diesel Exhaust Fluid

Other reasons for VW’s clean diesel lie boil down to the act of refilling its vehicles’ diesel exhaust fluid being a “turn off” to customers. The part-urea, part-water mix that is DEF is a key factor in reducing NOx emissions, and its periodic introduction into the vehicle’s exhaust aftertreatment system via dosing is a vital part of the selective catalytic reduction (SCR) process. But precise DEF dosing can be extremely difficult to calibrate and excessive urea injection can culminate in elevated ammonia emissions (also known as ammonia slip) at the tailpipe. However, forgoing DEF usage almost completely doesn’t really explain a strategy of erring on the side of caution, but rather not even attempting to solve the NOx problem. Of course, Volkswagen also assumed that no one would ever test—or have the proper means to test—its cars out in the real world and find out the truth.

First Discovery: 2014

Diesel Emissions Test Cell

After securing a grant to study the emissions of diesel vehicles, a small team at West Virginia University’s Center for Alternative Fuels Engines and Emissions (CAFEE) began testing Volkswagen TDI models using its mobile emissions equipment. The group soon found mysteriously wide gaps in NOx emissions between standardized testing (performed in a lab and on a chassis dyno) and real-world driving. By comparison, the diesel-powered BMW the team was also evaluating produced real-world emissions that mirrored what it had done in standardized testing. After quadruple-checking its work and then some, the team contacted the Environmental Protection Agency (EPA) and the California Air Resources Board (CARB).

A Second Opinion

California Air Resources Board

Backing up West Virginia University’s findings, CARB performed lab testing on a fleet of Volkswagen Jetta and Passat TDIs. Upon manipulating the cars’ control systems into believing they were out on the open road rather than strapped to a stationary chassis dyno, even more damning evidence of cheating was uncovered. Oddly, the cars were found to emit less emissions when cold than when they were up to operating temp—something that never happens. CARB’s findings ended up being the smoking gun that forced VW executives to admit to the cheating.

Do The Effects Of NOx-Fighting Devices Explain Why VW Avoided Using Them?

Carbon Buildup Volkswagen TDI Diesel

Put simply, they cheated. But even though they did cheat we don’t know how old (i.e. “used”) the test subjects used by both WVU and CARB were. In any modern era internal combustion engine, especially a diesel engine saddled with an exhaust gas recirculation system whose job it is to curb NOx emissions, the reality is that emissions output increases steadily throughout the life of the engine. It’s a fact that aside from engines that undergo regular emissions system cleanings, very few engines burn fuel as efficiently and operate as cleanly as they did the day they left the dealership. The same goes for performance and fuel efficiency, which are essentially gradually in decline from Day 1, although the driver will likely never notice.

EGR Soot Volkswagen Jetta TDI

As EGR systems accumulate service hours, intake systems and cylinder heads become more restricted due to carbon buildup and the EGR system itself becomes less efficient. This means more NOx pollutants are allowed to exit the tailpipe. This isn’t an attempt to justify VW’s deceit, because that’s inarguable, but it begs the question of whether or not a test fleet of brand-new TDI’s would’ve yielded NOx emissions 40 times higher than advertised. In the opinion of this writer, brand-new Volkswagen diesels should have been tested in a separate, independent study for what you might call a control group. If nothing else, comparing the data between a new VW equipped with illegal software to another illegal sedan with 80,000 miles on the odometer might’ve been interesting.

Colossal Buyback Program

Volkswagen Jetta TDI 2014 Diesel Car

For Volkswagen, the civil penalties resulting from Dieselgate amounted to more than $20 billion in the U.S. alone. And it also prompted one of the biggest, most expensive vehicle buybacks in automotive history. The $10 million buyback program allowed certain VW owners to sell their car back to the automaker, lessees to obtain a cash value and owners wishing to hold onto their VW a free (to them) emissions fix, plus compensation of up to $10,000 to cover depreciation.

If History Doesn’t Repeat, It Rhymes

Nitto Neo Gen 215-40R18

Let’s face it, Volkswagen’s scandal was anything but the first time a major automaker has been exposed for skirting around emissions regulations. GM was caught red-handed in 1995 and Cummins, Navistar, Caterpillar, Detroit Diesel, Mack Trucks and Volvo were found guilty of violating NOx emission standards in 1998. All were accused of programming engines to produce less pollution during testing than when operating in real-world conditions. The civil penalty back then was $1 billion—and for whatever reason, there wasn’t a lot of noise. Long story short, while lessons were learned during Dieselgate, defeat software isn’t going anywhere. The question is which manufacturer will be caught next.

  • On the bright side, the predecessor to Volkswagen’s 2.0L diesel, the ALH code 1.9L TDI wasn’t tainted by the Dieselgate scandal and continues to enjoy a solid reputation for reliability, cleanliness and horsepower potential.
Return to beginning of article

Recommended For You

Loading ...