Can Clean Diesel Survive the Volkswagen Scandal?
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Can Clean Diesel Survive the Volkswagen Scandal?

Diesel never really took off stateside, and now some experts question if the Volkswagen scandal is a death knell for the future of clean diesel.

America has never been partial to diesel. The image of the loud, rumbling, black-smoke-spewing diesel vehicles of the past created a stigma that has been near impossible to shake. Clean diesel was supposed to change all that.

But in the wake of the revelation that Volkswagen had been cheating on emissions tests to hide the shockingly high levels of toxins spewing out of its "clean" diesel vehicles, many are left wondering: Was truly clean diesel ever a possibility? And what does the future hold now for diesel in America?

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"One diesel cheat is everybody's diesel failure," said Margaret Wooldridge, a mechanical engineering professor and engine expert at the University of Michigan.

The dream of clean diesel is beautiful: midsize, comfy passenger cars that combine the fuel mileage of a hybrid with the power of a pickup truck, while curbing all the sooty pollution we associate with diesels. Industry experts were sure this would shift the tides for diesel in America, allowing us to catch up with Europe, where diesel vehicles currently make up about half of the market. In 2006, J.D. Power & Associates predicted diesel to have a 12 percent market share in the US by 2015, according to the Washington Post. In reality, clean diesel didn't change much of anything: diesel vehicles represent around 3 percent of the US market today—the same as they did in 2006.

"The numbers are already really, really small," Wooldridge told me over the phone. "You're talking about a very small piece of the pie becoming, perhaps, a tiny bit smaller."

Stigma has definitely played a role in making American drivers hesitant to buy diesel vehicles, but it's not the only reason they never took off, Wooldridge said. Cost was a huge deterrent. Although diesel was historically the more affordable fuel, diesel prices have generally been higher than gas prices for the last 11 years. This is due to a confluence of factors, including an increased global demand for diesel, the US shift to ultra-low sulfur diesel, and federal taxes, which are six cents higher per gallon for diesel compared to gas, according to the US Energy Information Administration. Each time a diesel driver goes to fill up—even though it's often less frequent than with gas cars—they're paying more than their gas-pumping neighbor.

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There's also an upfront cost of $1,000 or more, Wooldridge said, because diesel engines are more expensive to make.

"So drivers see a bigger upfront ticket price, they see a higher fuel cost, and I know very few people who make their decisions based on the sticker in the window giving the fuel economy information," Wooldridge said. "That's all serving to prevent diesel from making more headway in the US."

That price restraint-fuelled hesitancy was only buttressed by the ghost of the soot-spewing diesel clunker. Now with the knowledge that Volkswagen's clean diesel was anything but, that spectre looms even larger. We now know that to achieve the impressive mileage Volkswagen's diesel fleet boasted, without requiring drivers to periodically top up diesel exhaust fluid, the cars were dumping as much as 40 times more nitrous oxide into the atmosphere than US regulations allow. And while carbon dioxide is the most abundant greenhouse gas, and diesel vehicles emit significantly less CO2, nitrous oxide is arguably more dangerous: the EPA says "the impact of one pound of N2O on warming the atmosphere is almost 300 times that of one pound of carbon dioxide."

Given the huge gap between what Volkswagen said their cars could achieve and what they actually were doing, was there ever a chance Volkswagen could have delivered on the promise they sold?

"They could do it, but not at the right price point. They wanted their vehicles to be a better financial deal for their buyers," said Bruce Belzowski, an automotive futures expert the University of Michigan's transportation research institute. "I don't think it's a matter of the technology not being there, but the cost of adding the technology makes it more expensive and also you don't get quite the fuel economy that VW was getting."

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Though Volkswagen hasn't revealed why it tricked emissions tests, experts have speculated that the vehicle systems used to skim nitrous oxide out of the exhaust used up too much power, making the cars less fuel efficient (and possibly even less fun to drive). Some clean diesel vehicles inject a urea solution to convert nitrous oxide into less dangerous emissions, but these systems increase the upfront cost and also require drivers to top up the urea fluid. Volkswagen instead was using a filter to trap the nitrous oxide, which was turned off when the vehicle wasn't in testing. In order to crank up the technology enough to meet emissions standards and preserve the car's power and efficiency, VW would probably have had to also crank up the price.

Clean diesel isn't an impossible dream, but Volkswagen's exact iteration of it may have been. So where do we go from here? Belzowski and Wooldridge both predicted that diesel will still have a market in midsize working trucks that need the extra power to tow and haul, but the US public's view of diesel may have dipped far enough that we'll never meet the 12 percent market share J.D. Power & Associates predicted a decade ago. Still other experts hold out hope.

"Ten years down the road, people will have forgotten about this," said John Reisel, an associate professor in the Department of Mechanical Engineering at the University of Wisconsin-Milwaukee.

Reisel said there may be some public distrust in diesel, and even in our emissions testing process, but if Volkswagen reacts quickly to fix the problem, it could be smoothed over. The bigger issue, he said, is those initial barriers that stopped diesel from taking off stateside in the first place: cost and stigma. Only if we shift our thinking about what we want from our cars will the market start to budge, Reisel said.

"If people start worrying more, like they should be, about carbon dioxide emissions, that's where people may turn back to thinking about diesel," he said. "I don't think it's the death of diesel."