Fri 22 Mar 2019
John German had not been looking to make a splash when he commissioned an examination of pollution from diesel cars back in 2013. The exam compared what came out of their exhaust pipes, during the lab tests that were required by law, with emissions on the road under real driving conditions. German and his colleagues at the International Council on Clean Transportation (ICCT) in the US just wanted to tie up the last loose ends in a big report, and thought the research would give them something positive to say about diesel. They might even be able to offer tips to Europe from the US’s experience in getting the dirty fuel to run a little cleaner.
But that was not how it turned out. They chose a Volkswagen Jetta as their first test subject, and a VW Passat next. Regulators in California agreed to do the routine certification test for them, and the council hired researchers from West Virginia University to then drive the same cars through cities, along highways and into the mountains, using equipment that tests emissions straight from the cars’ exhausts.
It was clear right away that something was off. At first, German wondered if the cars might be malfunctioning, and he asked if a dashboard light had come on. That didn’t really make sense, though – the cars had just passed the California regulators’ test. His partners thought there might be a problem with their equipment, and they recalibrated it again and again. But the results didn’t change. Nitrogen oxide (NOx) pollution from the Jetta’s tailpipe was 15 times the allowed limit, shooting up to 35 times under some conditions; the Passat varied between five and 20 times the limit. German had been around the auto industry all his life, so he had a pretty good idea what was going on. This had to be a “defeat device” – a deliberate effort to evade the rules.
“It was just so outrageous. If they were like three to five times the standards, you could say: ‘Oh, maybe they’re having much higher NOx emissions because of the high loads,’” or some other external factor. “But when it’s 15 to 30 times the standards, there is no other explanation,” he says. “It’s a malfunction or it’s a defeat device. There’s nothing else that could possibly get anywhere close.”