After Volkswagen: Where Does Diesel Go From Here?

Volkswagen recently had to admit that 11 million of its diesel-powered cars are equipped with devices that intentionally cheat pollution tests. ODD ANDERSEN/AFP/Getty Images
Volkswagen recently had to admit that 11 million of its diesel-powered cars are equipped with devices that intentionally cheat pollution tests. ODD ANDERSEN/AFP/Getty Images

Volkswagen has done its reputation no favors by hiding lines of code in its diesel cars' programming to defeat federal regulators' emissions tests. Those lines of code made the engine into a low-emissions machine with pokier performance when it counted during testing, and allowed it to emit more pollutants while improving performance and fuel efficiency during everyday driving situations.

But has this dirtied clean diesel's reputation beyond repair? Elon Musk seems to thinks so. But then again he's the founder of electric car company Tesla. In the United Kingdom, car leasing company Flexed claims in a press release that people are actually citing the VW scandal as a reason to look into buying all-electric cars in recent weeks.


Diesel passenger vehicles only made up about 3 percent of sales in the United States on diesel's best day, and in recent years the price of gasoline has dropped rather than continuing its steep rise in the last decade. Then there's the fact that gasoline-powered cars usually cost a few thousand dollars less than diesel-powered cars when they're brand-new. Cheaper gasoline-powered cars and cheaper fuel are hard hurdles for diesel to overcome.

But as Allen Schaeffer, executive director of the Diesel Technology Forum, points out, “... clean diesel is a real thing. It's not something someone made up and didn't tell the truth about.” He also notes that manufacturers still have the new Corporate Average Fuel Economy (CAFE) standards to meet by 2025. In order to reach that 54.5 miles per gallon (23.2 kilometers per liter) target and the lower carbon dioxide requirement that comes along with it, all while still maintaining performance and load capacities in larger vehicles like SUVs and pickups — diesel is going to have to be part of the equation.

Kevin Downing at the Oregon Department of Environmental Quality specializes in the heavy-duty side of diesel, and he reminds us that this defeat device scandal isn't anything new. In 1998, heavy-duty diesel engine manufacturers found themselves facing a record $1 billion settlement for using software-based defeat devices to perform better on emissions tests while spewing illegal amounts of exhaust on the road. “We've been there and done that on the heavy side,” Downing says.

Downing and Schaeffer agree that the heavy-duty diesel market isn't likely to be affected by the VW scandal. About 90 percent of commercial trucks are powered by diesel. “It's the technology of work and the global economy,” says Schaeffer.

Passenger cars, however, may suffer in the short term before diesel might start bouncing back.

“VW has 40 percent of the market share for passenger vehicles in the U.S.,” Schaeffer says. “If they're taking the products off the shelf for some period of time, people will have fewer choices for diesel cars.” He also expects emissions testing will become more rigorous, and the Environmental Protection Agency has already changed its testing procedures to be more random and harder for software to predict.

Downing notes that studies performed in Europe have shown that since 2010, diesel engines have been outperforming gasoline engines when it comes to reining in toxic output. That's often thanks to selective catalytic reduction, which treats the exhaust with a chemical called urea. Volkswagen and Audi six-cylinder cars — the ones that aren't in hot water with the EPA — already use this system.