End of the road for diesel?

Three rapid-fire developments from the cradle of the German car industry pose big questions for the future of diesel power.

We know about Volkswagen’s fudging of emissions tests, an event that so far has cost it more than $US26 billion and is still being fought in courtrooms around the world.

The retrospective ‘fix’ is blunting fuel economy and performance, according to recently published, independent Australian tests.

Volkswagen contends this point.

In February a German court ruled the unthinkable was possible – a ban on driving all diesel cars in Stuttgart, home of Mercedes-Benz. Earlier, it was rumoured another Stuttgart powerhouse brand, Porsche, would soon cease production of all dieselpowered models, a move the brand has since officially denied.

The common element in all three events is the thermodynamically efficient diesel engine’s Jekyll & Hyde emissions profile.

Globally, carbon dioxide (CO2), a.k.a. a greenhouse gas, is the big climate change issue. Carbon dioxide, essential for life on earth, is routinely misreported as a ‘pollutant’. The good news is diesel engines produce much lower levels of CO2 than petrol engines. This earns plenty of green kudos and labels like ‘clean diesel’ – at least before the VW scandal.

The bad news is diesels emit high levels of nitrogen oxides (NOx) including the toxic nitrogen dioxide (NO2 ), greenhouse gas nitrous oxide (N2O) and nitric oxide (NO), which reacts with oxygen to form the fine particulate matter that diesel engines produce.

These micron-fine particles of carbon soot are so small they can lodge in the lungs and are known carcinogens.

VW admits to cheating the NOx tests and there is no doubt that the pollutant is a key contributor to air quality.

That’s why NOx is such a big local air-quality issue, along with particulates, in cities like London, Los Angeles and now Stuttgart.

The spiritual birthplace of the car, Stuttgart, exceeded safe pollution levels on 45 days in 2017, down from 63 the year before but still above the European Union’s requirement of no more than 35.

With roughly one in three German vehicles powered by a diesel engine, the ruling is a massive wake-up call for the industry.