What happened to the diesels Volkswagen had to buy back in the US?

The diesel scandal did tremendous harm to Volkswagen's reputation in America, a market that it tried to conquer with the promise of a 'clean diesel.'

EA189 engine (2008): This is the brilliant engine that may well have killed diesel. Though powerful & economical, VW's penny-pinching ensured it was not equipped with the technology to counteract high levels of harmful emissions. Instead, software in its Electronic Control Unit deliberately reduced harmful emissions only when the engine detected it was under emissions-test conditions. Around 11 million of these engines were built across many sizes.

Diesel was marketed by VW as a green option as well as a performance one. Diesel promised similar fuel economy to gasoline-hybrids like the Toyota Prius but with much better driving characteristics and more responsive power, and because diesel generally emits less CO2-per-mile than gasoline, a helpful choice in the battle against climate change.

In October 2013 we reported on how more stringent emissions regulations were going to hit diesel cars very hard; a year later the French government announced a big crackdown on diesels in a bid to clean up air in the country’s cities. This was just after London Mayor Boris Johnson had announced plans for an Ultra-Low Emissions Zone in the capital – targeting diesel engines in particular.

Both West Virginia University’s Center for Alternative Fuels, Engines and Emissions and the California Air Resources Board (CARB) had their suspicions generally that the diesels now joining American roads in large numbers were not as clean as advertised. The VW Jetta diesel performed as expected in lab test conditions, but on the road the Jetta started emitting much higher amounts of Nitrous Oxide (NOx) than permitted – by a factor of 15 to 35 times higher.

NOx is a key contributing factor to urban smog, and for geographical reasons the greater Los Angeles area is particularly prone to it (pictured), greatly exacerbated by very high car ownership, usage levels and congestion. So CARB takes a naturally strong view on NOx.

Volkswagen was alerted to the problem and obfuscated in response, blaming air pressure and test-route differentials. A recall and software upgrade was ordered, which took place in early 2015. However, while emissions were reduced, the cheat device remained, and emissions were still above US legal limits, as was shown when CARB tested 2012 Passat (an example is pictured) - that has been subject to the recall and supposed fix. The high emissions remained. Some at CARB became convinced that far from being a routine testing issue something more sinister was afoot.

After CARB repeated ever-louder questions to VW in the USA, in August 2015 a senior executive quietly confessed to the head of CARB’s testing lab that the diesel engine did indeed contain a defeat device installed to fool official emissions testing, explaining the high NOx figures seen, even after the recall fix. The EPA held a press conference on September 18, accusing VW of using the illegal device used on 500,000 cars in America and millions more around the world. VW’s share price dropped 31% within a week, and VW CEO Martin Winterkorn (pictured) resigned.

The legal settlement agreed between VW and the US government saw VW agreeing to fix or buy back all the 500,000 offending vehicles, at a total estimated cost of $15 billion. A September 2016 study suggested that the vehicles in question emitted between 3,400 and 15,000 metric tons more NOx than they should have done. In January 2017, VW agreed to pay a fine of $4.3 billion to the US government in civil and criminal penalties, and several executives are being investigated and some face prosecution.