Is D-day looming for diesel-fuelled cars?

Tougher air quality rules and city centre bans could push diesel engines to the brink of extinction

Major European cities, including London and Paris,  have proposed outrightbans on diesel cars

Major European cities, including London and Paris, have proposed outrightbans on diesel cars


When Rudolf Diesel, inventor and engineer, plunged to his death from the deck of a cross-channel ferry in October 1913, he left behind a mystery (did he jump or was he pushed?) and a legacy – a legacy of highly efficient compression-ignition engines that still have his lower case name.

Engines which have become, by a strange co-incidence, a metaphorical life raft for car makers in a sea of choppy emissions legislation.

As limits on climate-changing carbon-dioxide (CO2) grow ever tougher and tighter, so more and more of us are turning to the tax-and-fuel saving advantages of Dr Diesel’s innovation.

There is a problem though. Diesel fuel, by its nature, is less refined than more aromatic petrol, so while it burns more efficiently and more slowly, it also burns with less heat so more soot is then produced.

This soot, which shoots out of vehicles’ exhausts in the form of particulate emissions, is the Achilles’ heel of diesel.

It’s nasty, dirty stuff, hanging in the air on warm days (diesel fug) and sticking to the facades of buildings.

It’s also a lethal killer, with the American Union of Concerned Scientists saying “particulate matter irritates the eyes, nose, throat and lungs, contributing to respiratory and cardiovascular illnesses and even premature death”.

Although everyone is susceptible to diesel soot pollution, children, the elderly, and individuals with preexisting respiratory conditions are the most vulnerable. Researchers estimate that, nationwide, tens of thousands of people die prematurely each year as a result of particulate pollution.

Diesel engines contribute to the problem by releasing particulates directly into the air and by emitting nitrogen oxides and sulphur oxides, which transform into “secondary” particulates in the atmosphere.

“Diesel emissions of nitrogen oxides contribute to the formation of ground level ozone, which irritates the respiratory system, causing coughing, choking and reduced lung capacity. Ground level ozone pollution, formed when nitrogen oxides and hydrocarbon emissions combine in the presence of sunlight, presents a hazard for both healthy adults and individuals suffering from respiratory problems. Urban ozone pollution has been linked to increased hospital admissions for respiratory problems such as asthma, even at levels below the federal standards for ozone.”

Car makers have been working, manfully, to try to clean up the exhausts of their diesels to the point where a diesel engine, once seen as the dumb-headed cousin to a more sophisticated petrol unit, is now generally more advanced and more expensive to build. That extra cost alone has been putting pressure on diesel sales, but the big tripwire is going to be in air quality regulations.

Outright ban

Boris Johnson

Having floated the idea, Johnson backtracked and simply introduced a raised congestion charge price for older diesel-engined vehicles but the seed of doubt was well sewn in buyers minds by then.

Paris is carrying on with its plans for a total diesel ban by 2020 – given the huge number of diesel cars sold in the French market that’s going to cause a massive upset.

While Dublin City Council has made no comment on the issue (and is presumably still waiting to see how the removal of HGV traffic from the city centre is panning out pollution-wise) the fact is that where other major European urban centres lead, we often follow.

Besides, whether we here decide to implement a diesel ban or not, if a major metropolis such as London or Paris does so it will be enough to trigger major changes in the way cars are designed, built and sold across Europe.

While diesel’s low-carbon performance has brought the succour of lower road tax and cheaper tank-fills to many, the fact is that for all the multi-jet injections or DPF exhaust filters it’s dirty stuff to burn.

As one engineer from a leading car firm told The Irish Times: “We might save the planet from global warning by all turning to diesel but if we do we’ll all be too busy dying from cancer to enjoy it . . . ”

In the Guardian Fiona Harvey wrote: “Diesel emissions are now so bad that on several days earlier this summer, children, older people and vulnerable adults were warned not to venture outside. How long before this starts to have an effect on the economy?”

How long indeed? How long can we continue to sustain a 73 per cent weighting towards diesel cars in the Irish market if what we are doing is essentially slowly killing ourselves?

Well, that perhaps is a knee-jerk reaction.

Opel, once chided for the relatively poor quality of its ageing diesel engines, has performed a remarkable turnaround this past couple of year, introducing new engine families that are smoother and cleaner and far closer to the cutting edge.

Dave Sheeran, managing director of Opel Ireland, suggests that it’s too simplistic to blame consumers for buying the very diesel cars that tax regimes encouraged them into.


“Air quality is affected by a large number of sources, including home heating systems, non-road machinery, construction machines and so on. And, of course, also older cars and vans, especially if they are not properly serviced and maintained. Air quality is not improved by merely banning vehicles, especially when they meet the highest emission standards, such as Euro 6. We believe that diesel engines will always retain the advantage of higher thermodynamic efficiency over petrol engines.”

Indeed, this may be a rare case when the average motorist is actually not to blame for society’s ills. Public transport, and its reliance on diesel-fuelled buses, could actually be a far greater culprit when it comes to city centre air quality problems.

Nigel Humphries, a spokesman for pressure group Alliance of British Drivers, told The Irish Times: “”For almost two decades local authorities have used ‘smart travel’ programmes to encourage people to use buses and boost their revenues from parking charges, as well as attempts to implement workplace parking and congestion charges all aimed at car drivers. Effectively, they have a vested interest in maintaining the status quo.

Lobby groups

Sadly, there’s no easy answer nor solution to all this. The Irish car market is currently tilted massively towards diesel power as a result of the CO2-based motor tax and vehicle registration tax (VRT) regime introduced in 2008. To attempt to penalise all those who purchased diesel cars since then, believing that they were both helping the environment and saving themselves money at the pumps and at the tax disc, would be grotesque.

A major ban on diesel-engined cars in city centres would also have a catastrophic impact on the used values of diesel cars across the board, affecting many who rarely, even never, drive their cars in city centres.

Buses, HGVs and diesel-powered trains are far more to blame for air quality issues, it would seem, but unravelling the public transport network is simply not an option.

It may be that the car firm engineer was right all along. We’ll save the planet from CO2-caused climate change, but we’ll all be too busy dealing with cancer and respiratory issues to enjoy it.

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