The car industry on Wednesday launched a campaign to “challenge the increasing demonisation of diesel” vehicles.

The campaign, launched by the Society of Motor Manufacturers and Traders (SMMT), promotes the credentials of the new Euro-6 standards. This Europe-wide law, which will come into force in September, limits nitrogen oxide (NOx) emissions from new diesel cars to 80mg/km in order to bring down air pollution levels that breach health regulations in many EU cities.

Diesel cars have come in for increasing criticism in the last year for their larger-than-thought emissions of NOx and small particulates. Last year London mayor Boris Johnson proposed a scheme that would pay diesel car owners up to £2,000 to scrap their vehicle and switch to a cleaner model.

Diesel was supposed to be the answer to the high carbon emissions of the transport sector, a lower emitting fuel that was a mature technology – unlike electric or hydrogen cars. In the early 2000s the Blair government threw its weight behind the sector by changing ‘road tax’ (vehicle excise duty) to a CO2-based system, which favoured diesel cars as they generally had lower CO2 emissions than petrol versions.

It inspired British car makers to invest heavily in a manufacturing process that most countries outside Europe have ignored. In 1994 the UK car fleet was only 7.4% diesel. By 2013 there were 10.1m diesel cars in the UK, 34.5% of the total.

But studies have since shown that diesel cars’ emissions of other pollutants can have serious impacts on the health of people exposed to them.

Now the European Union is scrambling to reduce the impact of its massive diesel industry on the health of its citizens. Carmakers have had some success in cutting the particulate matter of their engines, but according to recent independent testing, NOx levels remain stubbornly high.

A Channel 4 documentary in January called the subsidisation of the diesel industry the “great car con”. In the programme the current shadow environment minister Barry Gardiner MP, who was a member of the Blair government, admitted the policy was a mistake.

“Hands up, can I say there’s absolutely no question that the decision we took was the wrong decision.”

In 2014 the European commission took the UK to court for regularly exceeding NOx limits in 16 zones from London to Glasgow.

In an attempt to restore consumer confidence the car industry has produced leaflets (available at car markers and dealerships) as well as a “myth-busting” website. The campaign shows the growth of the diesel market and claims success for car makers in reducing emissions of NOx, particulate matter and CO2.

Mike Hawes, SMMT chief executive, says: “Today’s diesel engines are the cleanest ever, and the culmination of billions of pounds of investment by manufacturers to improve air quality ... The allegations against diesel cars made in recent months threaten to misguide policy making and undermine public confidence in diesel. It’s time to put the record straight.”

But the claims of the industry have been criticised by experts who say the numbers cited by car makers are based on a test that does not represent real-world conditions. For official standards, diesel cars have their emissions tested in a laboratory, but recent testing by the International Council on Clean Transportation found:

On average, real-world NOx emissions from the tested vehicles were about seven times higher than the limits set by the Euro-6 standard. If applied to the entire new vehicle fleet, this would correspond to an on-road level of about 560 mg/km of NOx (compared to the regulatory limit under Euro 6 of 80 mg/km).

The Euro-6 regulations require a real-world test to be introduced, but the timing of this is still being debated. Greg Archer from campaign group Transport & Environment says the car industry has successfully lobbied the European commission to have the likely date for an introduction moved back from 2017 to 2020.

“They’ve based it on limits and tests which are carried out in laboratories and don’t represent the amount of pollution that these vehicles actually produce on the road. And they know that.

“Carmakers are trying to greenwash dirty diesel to hide the truth that compared to a petrol car a typical new diesel car on the road emits 10 times more nitrogen oxides. While carmakers claim modern diesels are clean they are pushing to delay and weaken the introduction of new pollution tests. This is because most new diesels can’t reach the limits agreed back in 2007 without fitting new technology,” says Archer.

An SMMT spokeswoman denied the industry was pushing back on real-world testing. To the contrary, she said, they were very supportive of getting the regime in place “as soon as possible”.

“We are waiting for a finalised communication from the European commission, which will set the parameters for the real-world testing. Until we have sight of that, manufacturers cannot commence the additional engineering investment required with any degree of certainty.”

Ben Barratt, an air pollution expert from King’s College London, says the early implementation of the new test is critical for the success of the regulations.

“In the absense of a real-world test we have to question these figures because history shows us that past performance has not delivered,” says Barrett.

“The sooner the real-world test comes in the better, without doubt. Because we will not know whether to trust the Euro-6 figures until that test comes in. Cities around Europe are reliant on Euro-6 delivering the reductions it is supposed to. If Euro-6 doesn’t deliver then many parts of Europe, including London and other cities in the UK, will continue to fail to meet European Union air quality standards.”

Councils around the country are beginning to take action to discourage their residents from buying diesel cars. Islington council will introduce a £96 per year diesel vehicle parking surcharge on 1 April. It will be the highest charge of its kind in the country and one of the first such schemes introduced.

Councillor Claudia Webbe said: “Pollutants in diesel exhausts have been linked to heart and lung diseases, which are major causes of serious and long-term health issues and even death in Islington, and the surcharge will encourage a move away from diesel.”



But Hawes said the charges made “no sense from an environmental point of view” citing the results from the tests the car industry agrees are flawed. The chairman and managing director of Ford of Britain, Mark Ovenden, says the charges are an unnecessary interference in the market.

“We support customer choice and the market should determine the best technologies for meeting CO2 and air quality goals,” he says.

But the car market is far from even. The carbon emissions tax regime currently levies £180 on a new petrol-powered Ford Mondeo. The rate for the diesel version is £0. Last month the UK government rejected an environmental audit committee recommendation to remove the tax advantage enjoyed by diesel cars. Signalling it remained supportive of the diesel industry.

The SMMT document also says that the furore over diesel’s contribution to air pollution is overblown, given the relatively small contribution (14%) cars make to the nation’s overall NOx emissions. There is a large misconception over who is the real villain, says the website. More than half of those survey by YouGov incorrectly identified cars and commercial vehicles as the biggest cause of air pollution in the UK.

“It would take 42m Euro-6 diesel cars (almost four times the number on the roads) to generate the same amount of NOx as one UK coal-fired power station,” says the Diesel Facts website.



But Archer says this is “another example of the car industry greenwashing the figures”. Where the pollution is occuring is more important than how much, he says.

“The pollution that comes out of [power stations] is highly disperesed. It’s rather different when you’re a child in a push chair being pushed along a curb breathing in the exhaust fues which are coming out of the cars standing next to you. So in terms of exposure to pollution, vehicles are far, far more important than power stations are.”