Sarah Uzzell with her new car.
Sarah Uzzell (pictured above) bought this new diesel VW in July. Once she learned of VW's scandal, she tested her car's pollution at N.C. State University. Photo courtesy Sarah Uzzell


It happened a couple of years ago, and it seemed so improbable … except it wasn’t.

By Gabe Rivin

When Sarah Uzzell went car shopping in July, she had the outdoors in mind. Uzzell enjoys camping alongside her dog, and so she wanted a car with plenty of space. Good gas mileage was a plus too.

Sarah Uzzell with her new car.
Sarah Uzzell (pictured above) bought this new diesel VW in July. Once she learned of VW’s scandal, she tested her car’s pollution at N.C. State University. Photo courtesy Sarah Uzzell

Uzzell, a resident of Raleigh, did her due diligence as a shopper. When she finished her research, the pick was clear.

She went for a 2015 Volkswagen Golf SportWagen TDI. The color: tungsten silver.

For Uzzell, the fuel-efficient diesel car seemed like a great fit. But a lot can change in three months.

“It’s a little less of a good choice at this point,” said Uzzell.

Volkswagen has faced immense scrutiny since mid-September, when the federal government accused the company of cheating air pollution tests for newer diesel cars.

Volkswagen installed software detecting when its cars were undergoing emissions tests and limiting pollution in order to meet the tests’ pollution requirements, the U.S. Environmental Protection Agency alleged. But under normal driving conditions, the software switched modes and allowed the cars to release significantly more air pollution.

Volkswagen has confirmed the EPA’s accusation to be true.

When driving in normal conditions, VW’s cars released up to 40 times the legal limit of nitrogen oxides, the EPA found. The finding is significant because nitrogen oxides contribute to the formation of smog, which can worsen health conditions including asthma and emphysema and can cause chest pain and throat irritation.

The unfolding scandal has upset car owners like Uzzell, who says she’s disappointed that the pollution fixes could affect her car’s performance.

“That’s not really the car I bought,” she said.

So to learn what she did buy, Uzzell is taking an unusual route. She’s one of several people who have taken their diesel VWs to Chris Frey, an engineering professor at N.C. State University, who’s testing the cars in order to show what exactly leaves the tailpipes when the cars are driven in the real world.

An oversight in the classroom

An outsider might guess that this is Frey’s first encounter with poor-performing diesel VWs.

To measure pollution from tailpipes, Frey uses a small probe, which shuttles pollution samples to the PEMS system.
Chris Frey, an engineering researcher at N.C. State University, measures pollution from tailpipes. To do it, he uses a small probe, which shuttles pollution samples to the PEMS system. Photo courtesy Chris Frey

Yet before EPA accused Volkswagen of a conspiracy, and before West Virginia University researchers released a study that helped expose the scam, Frey had already measured high amounts of pollution in a newer VW diesel car.

That was in February 2013. The only problem was, Frey didn’t yet realize what he had on his hands.

In his classes at N.C. State, Frey teaches students how to measure cars’ pollution in normal, everyday-driving kinds of conditions. For one of those classes, in 2013, Frey and his students tested a 2012 Jetta TDI wagon.

“It was touted as being a very clean vehicle with supposedly low emissions,” he said.

But when they measured the diesel car’s tailpipe emissions, something seemed amiss.

“The results were a little surprising in terms of the emissions of nitrogen oxides being very high compared to other vehicles we’ve measured,” he said.

Frey has tested more than a hundred cars for pollution. Some cars release high levels of pollution, owing to a failed component. But those, Frey said, are anomalies, which is what he suspected of the diesel Jetta.

And so he and his students moved on to test other cars.

Frey uses a portable system that provides second-by-second analysis of tailpipe emissions.
Frey uses a portable system that provides second-by-second analysis of tailpipe emissions. Photo courtesy Chris Frey

Two years later, news of VW’s scandal broke. Frey had a couple of immediate reactions to the story.

“One was the Homer Simpson ‘d’oh!’ moment,” he said. “My other reaction was, this is why a number of people in groups across the U.S. do this kind of in-use measurement, in part to verify that under real-world conditions, vehicles are performing the way we all think they should be performing.”

As the revelations about VW continued to cascade, Frey continued this work, showing what comes out of a VW’s tailpipe when it’s driven in the real world.

Road test

“The PEMS device looks like a suitcase,” Frey said. “We run a sample probe that goes into the tailpipe, and it’s basically a hose that we extract a small sample of exhaust gas [from]…. We run that hose around the back end of the car, through the back window and connect it to the PEMS.”

A PEMS, or portable emissions measurement system, is what Frey has used to measure VW cars’ tailpipe pollution under circumstances that more closely approximate real-world driving. With this technology installed, Frey has run a handful of newer diesel VWs through a lengthy route, one that spans 110 miles through the Research Triangle area.

That kind of testing is important, Frey said. VW was able to cheat in part because federal emissions tests are predictable, and VW was able to program cars to recognize when they were – and weren’t – going through the tests.

Yet driving through Raleigh’s traffic is anything but predictable. And that’s why Frey has been able to take a more accurate measurement of the VW diesel cars’ exhaust.

Chris Frey, an engineering researcher at N.C. State University, has measured high levels of nitrogen oxides in Volkswagen's newer diesel cars.
Frey measured high levels of nitrogen oxides in Volkswagen’s newer diesel cars several years ago, but chalked it up to an anomaly. Photo courtesy Chris Frey

Unsurprisingly, Frey has measured high levels of nitrogen oxides. Still, it’s difficult to say what effect VW’s cars have had on North Carolina’s air quality. For one, there are numerous sources of nitrogen oxides throughout the state, from 18-wheelers to coal power plants to hybrid cars.

To complicate the picture, North Carolina’s state government does not have pollution data on diesel VWs affected by the scandal. That’s because under current law, only gasoline-powered cars must go through annual emissions inspections, according to Tom Mather, a spokesman at the Department of Environmental Quality.

Frey admitted that the overall number of cars in North Carolina is large, and so the issue is one of fairness.

Frey pointed toward one VW he measured, a 2010 Jetta sedan.

“That car is emitting on average about 13 times more nitrogen oxides than, on average, what we see from gasoline vehicles that we’ve measured,” he said. “It’s not fair that that vehicle is emitting so much more. It’s basically equivalent to 13 vehicles in terms of its nitrogen oxide emissions.”

Car owners like Uzzell, the Raleigh resident, will have to wait as VW plans its response for the nearly 500,000 cars in the U.S. releasing excess amounts of pollution. Until then, Uzzell is hoping Frey’s test data will support a larger cause: a civil lawsuit against Volkswagen. When interviewed, Uzzell hadn’t yet received her results.

Uzzell doesn’t relish the fact that her car may be a heavy polluter, or that it may lose power if its emission controls are properly restored. Despite this, she still thinks her Golf is her best bet.

“It’s still a really great car to drive, even though it has terrible emissions,” she said. “But I carpool, so it balances all right.”

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Gabe is our former environmental health reporter from 2014-2016. He is a former editor of The Cooperative Business Journal, and a former reporter for Inside Washington Publishers, where he covered federal...