It has become increasingly more evident that carmakers must take aggressive steps to ensure that diesel cars and light trucks meet current environmental regulations.

Tests done by Emissions Analytics found that the majority of new diesel-powered cars sold in Europe do not meet the Euro 6 emission standards for nitrogen oxides (NOx) in real-world use.

Worse, some of them emitted as much as 12 times the current levels when tested in real-world driving—and didn't meet even the far lower Euro 3 standards from decades ago.

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Diesel vehicles have been under more scrutiny since the world’s largest car manufacturer, Volkswagen Group, was caught using "defeat device" engine-management software to pass tests.

Emissions Analytics EQUA Air Quality Index showing diesel testing results, April 2017

Emissions Analytics EQUA Air Quality Index showing diesel testing results, April 2017

The deception was discovered by the University of West Virginia’s Center for Alternative Fuels Engines and Emissions (CAFEE) during independent research trying to prove that automakers could meet the NOx emissions standards.

Emissions Analytics, like CAFEE, tested vehicles independently under real-world conditions to see if they met the new Euro 6 standards. Their disturbing results are published by the EQUA Index.

The Euro 6 standards came into effect within the European Union in September 2015.

They required all new cars sold from that date to meet far stricter limits on tailpipe emissions of NOx, carbon monoxide (CO), hydrocarbons (THC and NMHC), and particulate matter (PM) among other substances.

For 30 years, diesel cars have been favored in many European markets as a way to reduce fuel consumption and combat global warming, because they emit less C02 than gasoline engines of comparable power.

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However, diesel vehicles emit more NOx and PM which have been linked to serious health issues, including heart failure and increased respiratory illness.

The Emissions Analytics real-world tests found that only 16 of 116 diesel vehicles tested meet the Euro 6 emission standards for NOx, as depicted in the EQUA Air Quality Index chart.

Ony 14 additional vehicles would have met the standards even if the less stringent Euro 5 standards were used, giving a total of just 30 vehicles meeting a now-obsolete regulation under real-world driving conditions.

Volkswagen TDI 'clean diesel' television ad screencap

Volkswagen TDI 'clean diesel' television ad screencap

But the most disturbing part of the results may be how many cars exceeded the limits by wide margins.

More than half the 67 vehicles tested met only the decades-old Euro 3 emission limits.

Against the newly imposed Euro 6 limits, 21 of the cars tested exceeded the maximums with emissions that were at least six times the allowable limits.

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Ten of the 21 worst-performing cars had emission levels 12 times or more the limits set under the Euro 6 standards.

In the past, results from other studies by Emissions Analytics have led to the passage of stricter regulations to ensure that vehicles actually meet the emission standards in real-world usage.

While EU regulatory bodies are considering real-world testing regimes, carmakers have fought for delays and exceptions—and enforcement remains up to the individual EU countries' regulators, which in the case of those with large carmaking industries has not proven effective.

— Tevin C. S. Grant, Esq.


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