The 4 biggest misconceptions about the Volkswagen emissions scandal

Hidden car emissions are a huge environmental and legislative problem, but pretending that Volkswagen is the only culprit isn't going to solve anything. 

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German car manufacturer Volkswagen has admitted that it faked emissions data for up to 11m of its vehicles, sold around the world. Now, it is facing plummeting stocks, criminal prosecution and millions of angry customers.

We're not arguing that VW was not culpable for what it did - misleading governments, regulators and customers alike. But, as you might expect in a scandal like this, there's more to the story than first meets the eye. In fact, car emissions testing around the world is a pretty murky business, and VW are not the only ones taking customer trust and environmental regulations lightly.

Misconception 1: The VW cars were emitting loads of carbon dioxide

First, a bit of science. While, as the Environmental Protection Agency has said, VW's cars were emitting between 10 or 40 times acceptable levels of pollution, this refers to levels of nitrous oxides (NOx), not carbon emissions. While this is very troubling - nitrous oxides are bad for our lungs, help form smog and are one of the molecules involved in the formation of ozone - it isn't carbon dioxide. 

Diesel engines - like those in the VW case - are more efficient because almost all the carbon in the fuel is burned away. However, in petrol engines, the leftover carbon molecules (like methane and carbon monoxide) burn away leftover nitrous oxides created by the heat of the engine. Diesel engines therefore give off more nitrous oxides than petrol engines, but because of their greater efficiency, they give off less carbon emissions per mile. In a broader sense, the hotter the engine, the more nitrous oxides produced - but the greater the efficiency.;

As you can see, car design is therefore a bit of a tradeoff: do you go for a more efficient engine with greater nitrous pollution, or the option with more carbon emissions but less nitrous oxides? Both are less than ideal - and it's not just VW which has to deal with this Catch-22.

Misconception 2: This is totally unheard of, part 1

As a result of this, car manufacturers must balance efficiency, cost, emissions regulations, and different types of pollution when they design a car. This is why it's unsurprising that they're keen for emissions tests with built-in loopholes.

In Europe, for example, emissions and efficiency testing is far less stringent than in the US. During efficiency testing, manufacturers can test a special "pre-production" model of their car (called a "golden car" in the industry, presumably for its ability to make manufacturers money) in a lab. Loopholes in the tests also allow manufacturers to adjust the brakes, remove wind mirrors, use special lubricants and tape up any gaps to improve the car's efficiency before testing.

The UK's Advertising Standards Agency has said car efficiency and emissions data are "misleading", as it doesn't reflect how the car operates in the real world.

Misconception 3: This is totally unheard of, part 2

Consumers mess with cars' emissions levels, too. Diesel vehicles sold post-2008 are fitted with a special "diesel particulate filter"(DPF) designed to stop some of the nitrous oxide escaping, but if the filter gets clogged, it can affect the car's running and cause expensive damage. Drivers also must pay to have the filters cleaned. As a result, drivers often remove the filters - and some garages even remove them as an advertised service.

In 2013, the UK government introduced legislation which meant that any diesel vehicle with its DPF removed would automatically fail its MOT. However, Radio 4's You and Yours found that an inner part of the filter can be removed, while the filter still appeared intact, so inspectors can be fooled quite easily.

(These filters only begin to work after the engine has been running consistently for around 15 minutes. This is why diesel engines are better used on long, motorway based journeys, but emit huge amounts of pollution while stopping and starting in busy city centres. It's also probably why Oxford Street has one of the highest levels of particulate and nitrogen dioxide pollution in the world, and why mayors worldwide are considering banning diesel vehicles from city centres.)

Misconception 4: Politicians are shocked and horrified by the scandal

The loopholes in regulations are bad enough, but politicians across the US and Europe have actively encouraged them, usually because they're keen to stay onside with car manufacturers and the money they bring to their economies.

As the Guardian reported earlier this week, the UK, France and Germany have all lobbied in the past to keep loopholes in equivalent car emissions tests in Europe. France and Germany pushed for tests to be conducted on sloping downhill tracks, and Germany lobbied for manufacturers to be able to declare a final CO2 value 4 per cent lower than the one measured (because that's how measuring stuff works, right?). In the wake of the VW scandal, the European Parliament's environmental committee has voted to introduce new, "real world" emissions tests by 2017.

Hidden emissions are a huge problem, and we desperately need better estimates of what impact our vehicles are having on the environment. However, our open-mouthed insistence that VW is the only culprit isn't going to solve anything, and could allow the murky world of emissions testing to carry on unchecked.

Barbara Speed is comment editor at the i, and was technology and digital culture writer at the New Statesman, and a staff writer at CityMetric.