Diesel cars 10x more polluting than trucks

Actually, umm, no, that’s not quite true:

It found that heavy-duty vehicles tested in Germany and Finland emitted about 210mg NOx per kilometre driven, less than half the 500mg/km pumped out by modern diesel cars that meet the highest “Euro 6” standard. However, the buses and trucks have larger engines and burn more diesel per kilometre, meaning that cars produce 10 times more NOx per litre of fuel.

Fiddling with the numbers there then.

28 thoughts on “Diesel cars 10x more polluting than trucks”

  1. Bloke in North Dorset

    I don’t understand that paragraph at all. What does “the buses and trucks have larger engines and burn more diesel per kilometre,” when they are measuring per Km?

    As for the rest of the article they don’t seem to understand the difference between a standard and a test to meet the standard.

  2. well, if a truck only produces 210mgNOx per km vs a cars 500mgNOx per km … but 5he truck burns more fuel per km in its bigger engine that makes an even stronger case …

    … stronger case, but not a surprise. a bigger diesel engine runs hotter, and the more complete fuel burn means Less NOx production, this is well known

    Just like an 80 foot long power plant combustion turbine produces less pollution (and extracts more heat resulting in shaft horsepower) per unit fuel burned than the 5 or 6 ft long jet turbine attached to an aircraft

    giant engine vs small engine? apples vs oranges

  3. It’s really badly worded but it makes sense.
    210mg/km @ 2.5km/l vs 500mg/km @ 10km/l
    is eqv’t to
    525mg/l vs 5000mg/l.
    There’s your 10:1

    And TonyC, hotter is more efficient thermodynamically but causes more NOx emissions (because the really strong N-N bond is a bit easier to break with the extra energy). Thus EUROn regulations have (along with other stuff) forced manufacturers to run engines cooler and less efficiently. So it’s not that.

  4. Only one post in TRUK so far as of 9:25 today but its a beauty – ‘A lesson to economists’ (from a man who baled out of an economics course in Year one at university) It is of course crying out loud for a hefty fisking. Here’s a taste of the Spud (who to his ‘credit’ has started the year with a fusillade of gems illustrating his desire to retain his position as ‘the most ignorant commentator extant in cyberspace today’)

    ‘The Bank may well be right to believe that Brexit will adversely impact future earnings in the UK. I think they are. But the reality is that this perception is not widely shared. As a result people have refused to behave as if a downturn is coming. Based on the evidence this may be irrational, but that’s what is happening. ‘

    Those confounded people refusing to believe not only the BOE, but even more crucially, me, me, ME!! ME!!!! Time, I think for a tirade about ‘mainstream economics’ based on my two terms at Southampton.

    ‘This behaviour is completely contrary to almost all forms of economic modelling that assumes that current well being is the discounted consequence of future actions. The necessity for economists is to realise that their models just do not reflect not how people are. And economists also need to accept that people are not being irrational in behaving like this. ‘

    Obviously this is both a straw man as regards conventional economics and could certainly be applied to any of his published output – Which fails to recognise disincentives, has no regard for second order consequences, and assumes everyone is entirely selfless and good natured. Oddly by this critique Murphy has effectively removed himself from being worthy of consideration on any economic matters. He is of course too dim to realise this.

    ‘The error then is, again, in the economist’s modelling. The assumption that there is a ‘normal’ state to which we will return, which has been such a theme of post-crash economic dialogue, is just wrong. We won’t. We can, and we should, go somewhere else now.’

    It’s entirely possible we should move in a different direction. This is again not something ever considered in his writings on either the joy of Tax or Courageous State which assumes therefore that the state will retain a huge stake in all aspects of the economy and taxation levels must, as a matter of principle remain high. So, while he might be partly valid on conventional economic models (I happen to think he is creating strawmen to weather Brexit as best he can) his own model is subject to the same criticism magnified by a factor of 100.

    ‘And that is why they also don’t trust global companies that base such a large part of their earnings on trying to capture today the consequence of future transactions, whether by M&A profits or by financial engineering. Implicitly people know these activities, the rewards paid for them, and the profits that are declared by them are all unreal, using that word in various ways. They appreciate what economists don’t, and that is that all this complexity is faux: value is not made by discounting the future. Value is made by doing the right thing now in the light of the uncertainties that we face which we may not be able to quantify but which we believe to be real. ‘

    I think both the FTSE and Dow Jones have hit record highs in the last month. He appears to live in some kind of parallel universe where no ‘ordinary people’ have any stack in company earnings on the stock exchange (for example) As with much Murphyian prose dissecting it can be tricky but I think if I saw someone writing it in an economics GCSE I’d tell him to go back and perhaps learn some basic principles (or even read the FT for a week) before putting pen to paper.

    ‘And when economists begin to appreciate that we may get better economics.

    We have to hope.’

    I agree we have to hope for better economics than anything generated by TRUK, or else we’d all better prepare for hard times ahead. Just breathtaking – and we’re only 6 days into the year….

  5. So Much For Subtlety

    So we should replace cars with Jitneys?

    Do these people think their nonsense through before publishing?

  6. NOx emissions from diesel engines can be eliminated by the injection of urea into the exhaust. I believe this is a requirement for trucks in the USA, and many trucks in this country (and on the Continent probably) are fitted to use this technology. You see the “Blue” stations at motorway services where trucks can top up their urea tanks.

  7. The issue of NOx pollution, thought to kill 23,500 people a year in the UK alone


    Show me the death certs

    Beyond that – the smaller diesel engines (aiui) run higher compression ratios and higher injection pressures in order to get their efficiency. Beyond that there is also the question of the amounts of AdBlue injected – a subject that has been swerved around by legislators and car makers as some gaming around the testing regimes has gone on…. and the car makers wanted to keep the AdBlue consumption (and hence tank size) down.

    It is interesting I think to look at hybrid fueling (gas + diesel) which John Lewis has been running on some trucks for what -nearly two years now?

  8. KevinS,

    Could motorists strap immigrants to the underside of their cars to inject urea into the exhaust? One could exchange a dehydrated migrant for a hydrated one at service stations.

  9. Don’t forget that it was the all knowing all powerful always correct State that decreed that we should all drive diesel cars ‘because they were more efficient’ and for many years taxed diesel lower than petrol to encourage people to do so. And also set road taxes in relation to CO2 emissions which favoured lower fuel consumption cars too.

    If they were wrong then why are they right now?

  10. I had a suspicion that once they’d got enough people onto diesel, they’d suddenly, magically find something wrong with it that they hadn’t spotted before and jack the eco-tax up.

    I mean, it isn’t like all the fumes come out of one place – like a little pipe on the back – making them easy to collect and analyse, is it?

  11. I had a suspicion that once they’d got enough people onto diesel, they’d suddenly, magically find something wrong with it that they hadn’t spotted before and jack the eco-tax up.

    That’s what all the Land Rover owners assumed would happen with LPG: if it took off, it would be taxed properly.

  12. One comment that shows the complete lack of knowledge of the subject: is that certification is done on ‘prototype’ vehicles…. That’s utter bollocks. Clearly the writer doesn’t know the differences between production intent and prototype.

  13. TimN,
    Indeed; but I’m still surprised that LPG hasn’t gained in popularity. I suspect the savings in fuel are outweighed by higher maintenance costs and/or lower resale value.

    Lorries, buses, and even large vans all use AdBlue these days – they couldn’t possibly pass the Euro 6 tests without it. Some large cars (Chelsea tractors and high-end saloons) need it too, but for normal cars the manufacturers reckoned they could just sneak under the limits by fine-tuning their engines and programming them to burn fuel more cleanly under test conditions. Technically they are correct; alas the U.S. authorities took a dim view of this, and promptly fined VW $14.8bn.

    Bear in mind that the manufacturers choose which car to send in for testing. This means they can build a hundred cars, test them all internally, then send the cleanest one to the official lab.

    In short, the car companies followed the rules; but the government set the rules badly. This has been known about for well over a decade, but it takes forever for governments to make changes.

  14. “In 2005 the legislation on diesel vehicles in the UK & Ireland and in the rest of Europe demanded a drastic reduction of NOx emissions. As a result of this, most new trucks, buses, coaches and vans built after 2005 have been equipped with SCR technology (Selective Catalytic Reduction). In short, If you have a purchased a new commercial vehicle that is manufactured to meet Euro IV, V or VI standards i.e. a truck, bus, coach or van, it will require AdBlue®.”

    No wonder they produce less than cars.

  15. The latest diesel NOx EU emission standards for passengar cars are 80mg/km (Euro 6 dated September 2014). This is less than 1/6 of the stated level in the article linked by Tim: “500mg/km pumped out by modern diesel cars that meet the highest ‘Euro 6’ standard”. Thus the article is wrong by a large factor in part of its argument that HGVs are already more strictly controlled than are cars.

    It is also the case that EU standards for HGVs etc are specified in grammes/kWh: a level that is very difficult to measure and to interpret. It is certainly extremely difficult to relate it to the 210mg/km mentioned in the article.

    Interestingly, that 210mg/km given in the linked article uses the term “heavy-duty vehicles”. This very likely covers a wide range of vehicle gross weights (think of a factor of ten, and also loaded and unloaded fuel consumption) and this effectively unknown factor would have a large effect on fuel consumption rates in urban traffic (with its need for acceleration after braking). Pollution from all urban traffic (cars too) is heavily affected by periods of being stationary or moving slowly in low gear – though cars (in fact all lighter vehicles) are likely to be more adversely affected than heavier vehicles when stationary with the engine running.

    It would be far better if all vehicles had standards based on grammes per litre of fuel consumed. That contains an implicit normalisation for different types, sizes and loads of vehicle; also leaving separate the issue of fuel efficiency, which has a different motivation better left to the judgement of vehicle purchasers.

    Next up, the issue of NO2 pollution is particularly an issue in high density urban areas – because of the concentration of pollution levels and effect on a higher population density. Here all traffic speeds are low (including stationary) and highly variable. In such places just what sort of genius is it that decided to specify pollution emission levels per unit distance travelled rather than per unit volume/weight of fuel used. Was it the same sort of genius that only a few years earlier specified diesel engines as the better-to-have fuel for cars – presumably on the grounds of lower CO2 emissions – including (in the UK) significant fuel tax difference in favour of diesel over petrol.

    Best regards

  16. “I’m still surprised that LPG hasn’t gained in popularity.”

    Not really. LPG needs extra tanks and equipment which take up space, so really only makes sense with large vehicles with large engines. So small relatively efficient cars are going to struggle to manage to have the conversion done – they might squeeze it in, but then have a car with no boot space at all for example, and/or no spare tyre, or have a tiny tank with hardly any range. Plus there’s the cost of the conversion to be got back, so if your car is efficient already the payback time will be considerably longer. Whereas a big car with a big engine will pay back the conversion quicker. But the rub of that is you are still running a big thirsty vehicle which is about 20% less economical on LPG than petrol anyway. So unless you ‘have’ to do a lot of miles in a large vehicle (for business purposes say), then it makes no sense to buy a large thirsty vehicle and convert to gas. You might as well buy a small economical vehicle that runs on petrol or diesel, and save far more money.

    I speak from experience, having owned and run a Range Rover V8 on LPG back in the late 90s early 00s, It was lovely to drive but financially it made no sense over a normal car without a conversion.

  17. A few years ago, about half of Brisbane taxis ran on LPG, due to state government mandate, which meant their boots could accommodate a handbag. Back then we often traveled with our youngest daughter and had frequent fights at the airport because we refused to squeeze all of us in the back so the front seat could take a suitcase. We insisted on a minibus or station wagon. We now have the same problem with Prius taxis which also have restricted boot space.

  18. Tim said: “Fiddling with the numbers there then.”

    It looks like it is true though.

    As far as I can tell this is a quirk whereby Euro 6 for passenger cars and Euro VI for heavy duty vehicles diverged in scope some time ago.

    The divergence is that Euro VI for heavy duty vehicles takes into account ‘off-cycle’ (real world) emissions using roadside/mobile testing as well as testing cycle emissions while Euro 6 just considers testing cycle emissions.

    This is a separate issue to VW being cheating bastards and the figures included in the ICCT briefing suggests to me that bad publicity, fines and regulator strong arming have prompted VW to make sure some of their cars perform as well on the road as they do in tests while no one else’s do, even though the regulations don’t appear to require it.

  19. re:LPG
    Gas isn’t perfect – but as a stopgap low emission fuel it is pretty good. Various Asian cities with air quality problems notably Hong Kong have adopted LPG / CNG with an assortment of outcomes.

    This report might be of some interest.

    I run several LPG fueled vehicles (van + small MPV) and am quite pleased with both the economy and the doubled oil change intervals…. Losing the spare tyre stowage is a very minor inconvenience. “Higher maintenance cost” isn’t something that I’m familiar with – although the motor trade in general seems quite superstitious about LPG….

    The cost of conversion in the UK has historically been inflated – but the Polish diaspora has seen the price fall….

    The next generation of engines look likely to change the game again

  20. Bloke in Costa Rica

    About 50% of the buses here are LPG and you can really tell the difference if you’re stuck behind one. And another thing: they’re quiet.

  21. @Nigel Sedgwick, January 6, 2017 at 2:30 pm
    “It would be far better if all vehicles had standards based on grammes per litre of fuel consumed. That contains an implicit normalisation for different types, sizes and loads of vehicle; also leaving separate the issue of fuel efficiency, which has a different motivation better left to the judgement of vehicle purchasers.”

    Sounds sensible, that’s why EU rejected it.

    Thanks for links

  22. My big bug bear in this is that Nox is a local polutant. UK car emissions standards are basically set to try and improve central London (H bomb might do the job better), where Nox emissions matter.

    On my commute over 20 miles of moorland, no-one cares about Nox and particulate levels, but the fuel economy of my car has been crippled anyway, to suit the standards of the inner city’s where it basically never ever goes. It’s a stupidly moronic waste of everyone’s money.

    Incidentally, a good deal of the modern Nox problem isn’t cars anyway – it’s high efficiency gas central heating ‘combi’ boilers… Guess which idiots made us all fit them, instead of older, less efficient types (with lower burn temperatures, and thus much less Nox output)

  23. Jim.

    Is completely right about LPG being better on a larger engined car. I ran an Audi S8 for 120,000 miles on LPG over 6 years. Financially it made real sense and the cost of the conversion was paid back in only 9 months. But the place I got my LPG from was really cheap 40p a ltr when a Shell station would have been 55p. Since then I have had a company car, which with a change of job means I will be looking at LPG again. Trouble is the conversion costs for a V10 Audi S8 are rather higher than for the old V8’s. My local LPG conversion company is looking at how to get a Prins conversion to work before I buy the car. MUCH MUCH lower nitrogen oxides though.

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