A different slant on the diesel car “BAN”

Posted on May 15th, 2015 by Rob Marshall

dieselJust like healthy eating advice that tends to vary wildly in its recommendations, the British public is now being told that previous car buying fiscal incentives might not have been such a good idea after all. With air pollution, mainly in London, failing to meet EU-set targets, and with British taxpayers having to stump up cash for potential fines, the guns of blame are being directed primarily at diesel passenger cars – models that our tax system has incentivised us to buy.

With their lower CO2 and annual VED rates, heavy-oil fuelled engines have been so popular that, in many cases, even some of today’s model line-ups do not feature a petrol-powered alternative. While diesel vehicles have always found favour with many business users, the British public were lured later by their increased efficiency and tax breaks that reduced carbon dioxide emissions bring. Since the late 1990s, carmakers have succeeded in making diesels more powerful, less polluting than before and super-efficient. However, focussing on greenhouse gases, instead of genuine pollutants, is proving to be a mistake.

Now, politicians are arguing that a diesel engine’s tendency to produce higher levels of genuine toxic emissions, NO2, NOx and particulate emissions in particular, (even though much of this is suppressed by sophisticated anti-pollution hardware, such as NOx traps, particulate filters –pictured- and EGR valves) is contributing to a major health hazard in our built-up areas. However, the emissions that diesel cars do not contribute are being ignored. Unlike petrols, diesel engines produce very little CO (carbon monoxide), for example, concentrated inhalations of which will cause death to set in far swifter than breathing in cancer-causing particulates, for example.

Somewhat ironically, recent developments to increase power and decrease carbon dioxide emissions of petrol cars have seen modern direct-injection spark-ignition engines emit up to 1,000 times more particulates than older-design petrol engines, according to TÜV Nord. For this reason, approximately 18 months ago, the lobby group, T&E (Transport and Environment) called for direct-injection petrol engines to be equipped with particulate filters. To my knowledge, no petrol model is for sale thus equipped, leaving me to conclude that petrols are far from being the saints that they purport to be. It also makes a potential diesel car scrappage scheme at least as wasteful of our earth’s resources as the previous exercise that ended five years ago.

It appears that politicians are looking to create sound bites and, as expected, have given their blessings to ultra low emission vehicles (defined by their CO2 emissions being below 75g/km) to solve Britain’s pollution problem. I say good luck to them! Plug-in hybrids and electric cars simply take power from our national grid system, which relies primarily on burning fossil fuels, thus simply moving (potentially more harmful) pollution from the city to less built-up areas. Also, when their petrol engines are running, it has been found that most ultra-low emission vehicles do not meet the stated economy claims by a wide margin – therefore, it is reasonable to presume that the stated emissions will be inaccurate as well. For example, Which? Magazine’s recent examination found that the highly popular Mitsubishi’s Outlander PHEV failed to achieve half of its official figure, while the Volvo V60 plug-in hybrid mustered 81mpg against its billed 155mpg.

I also worry about how toxic those extra emissions might be. A further problem with petrol engines that are not running for much of a typical journey in the city, which is usual in the urban drive cycle of a typical petrol hybrid, is that their catalytic converters might never reach their optimum working temperature, thus increasing the risk of untreated harmful pollutants being released into the atmosphere, a factor that is likely to have not been envisaged by the legislators.

I wonder how long it will be before there is another policy rethink, no-doubt at the cost of the average private motorist, when it is discovered that replacing diesels and older petrol cars with direct-injection petrols and hybrids are not suitable answers alone to reduce air pollution. For the time being, I would like to suggest that our authorities start enforcing the anti-pollution laws that are already in place. Firstly, by cracking down on owners and garages, with hefty fines, that take part in the popular and illegal activity of removing, or disabling, pollution reducing hardware (such as particulate filters and EGR valves), while also ensuring that engine tuning boxes and ECU chips can only be sold if they are tested and e-marked independently, to verify that they do not cause the vehicle to exceed its pollution targets set during its Type Approval. These measures would be a good start to demonstrate that the legislators are at least serious in ensuring compliance with the air pollution targets.