NOX vs MPG

[ProfJohnL]

I have decided to make this post becasue it touches on the subject of engine pollutants that has been discussed in some detail in the past, and I have used an assumption that now in the light of what follows seems to have been incorrect.

I had previously assumed that for properly adjusted engines that those have low MPG are likely to produce more pollution per mile. But a recent test conducted by the Consumer Associations has thrown that assumption aside.

The Association has conducted a test where they have compared the NOx production of different manufacturers products in two categories Euro 5 and Euro 6. They in each category they report a difference ratio of about 600% between the worst and best. The short report does not specifically state that all the models tested were Diesel, but that is the clear inference, as only the only fuel actually mentioned is diesel.

The report neither tells us models and engines sizes so the actual figures produced so the actual results are rather vague, but they do tell us

"It also might surprise you to learn that our unique testing has revealed there is no strong link between the level of emissions your car creates and its MPG (fuel economy). We’ve even found hybrids that produce high levels of toxic emissions.

Read more: http://www.which.co.uk/news/2017/03/which-tests-reveal-the-worst-diesel-cars-for-air-pollution/# - Which?"

Its important to understand the Which? report only looks at the NOx and whilst it is a serious pollutant, it's not the only one that we should be concerned with.

 

[camel]

There is more pollution in this world caused by coal fired power stations being built in the sub continent and China rather than diesel vehicles running round Europe, for Gods sake if people are that concerned about diesel emissions wear a smog mask, and if diesel is such a pollutant take the rubbish out of it at the refinery,

 

[travellerone]

Does anyone actually believe any of this when Euro 6 vehicle are allegedly putting out more harmful stuff than Euro 5 vehicles. The whole car manufacturer specifications and data on emissions, mpg figures are numbers influenced by marketing and sales departments.

 

[Dustydog]

Very good points there Prof.
I'd seen the Which? Report and indeed two earlier ones in the papers.
NOx is of course a generic term for a lot of nitrogen oxides.
Nitrous Oxide is not damaging to our health but other oxides only appear when it's light and apparently lead to smog and lung irritants.
I too had assumed low mpg reflected high pollution. Clearly not the case!
But why is the poor motorist pulled from pillar to post by Ministers who clearly have another agenda. Ie raise more money.
The VW debacle says it all. But no 0ne seems concerned about buses coaches lorries and trains and tobacco smokers who probably churn out more pollution than the motorist.

 

[ProfJohnL]

Hello Travellerone,

As I said you have to bear in mind the results of the Which? test were only looking at NOx, and there are other pollutants that in addition the Euro standards look for. So NOx is only part of a bigger picture.

Euro 6 is a tighter schedule than Euro 5 so compliance with Euro 6 will overall be less polluting than Euro 5. Its not uncommon to find that as a standard tightens certain aspects of the measurements may see some components increase whilst others reduce but overall there is net reduction.

Notwithstanding the VW Dieselgate scandal, sales and marketing can't change the emissions figures, so that conspiracy theory is something of a red herring.

 

[ProfJohnL]

.... if diesel is such a pollutant take the rubbish out of it at the refinery,

Its not that simple. A lot the pollutants are only created when the fuel is burned in a compression engine especially High pressure engines like diesels.

 

[camel]

And who's bed doe's 'Which ' sleep in , Ah, Ah , Which says this is the best of this or that, Which say's don't eat sliced bread on a Wednesday, Which say's don't breath today it is better for you health, :evil:

 

[Dodger524]

The report deals with Euro 5&6 engines but the latest diesels are Euro 7 & 8 I believe. Certainly some manufacturers such as Ford are lagging behind others.

 

[camel]

Would you not think that if the way forward was electric powered white van distribution, why did a major manufacture of electric vehicles in the UK recently,

 

[PaulT]

I'm probably being cynical but I wonder if the government's advice re diesels is intended to make us switch to petrol vehicles which use more fuel. More fuel used equals more tax income for the government.

 

[MichaelE]

The report deals with Euro 5&6 engines but the latest diesels are Euro 7 & 8 I believe. Certainly some manufacturers such as Ford are lagging behind others.

Currently the Euro 6 is standard and was introduced in September 2015. There is isnt a Euro 7 or 8 .
Ford arent lagging behind as simply they cannot sell a new car that doesn't reach the Euro 6 standard.

 

[ProfJohnL]

And who's bed doe's 'Which ' sleep in , Ah, Ah , Which says this is the best of this or that, Which say's don't eat sliced bread on a Wednesday, Which say's don't breath today it is better for you health, :evil:

Hello Camel,

Why the antagonistic attitude?

The report I have cited is not telling you what you should or should not do, it is merely offering an insight into the realities of the emissions.

My only connection withe tha CA is as a fee paying member, but I sincerely believe the Consumer Association is not "in Bed " with anyone except its membership. It frequently challenges businesses that let customers down and Government to strengthen the consumer's arm.

Regarding the tests they carry out. Their methods and techniques are well respected in the scientific and engineering circles. They often de mystify some of the gobbledygook some manufacturer's try to baffle us with, and they do real comparisons which you can't get anywhere else. Im not claiming they're faultless, but generally when they do make a mistake they're open about making an apology and making corrections.

Legally they are one of a very select group of organisations that the governemt allows to make "super complaints" becasue of their fastidenous, independance and the fact they have a wide access direct to the consumer.

 

[otherclive]

And here is something else to brighten your day: from TUV Nord

Direct-injection petrol engines should be fitted with particulate filters to combat their higher particulate emission levels, says environmental lobby group, Transport & Environment (T&E).
Recent research from the independent research institute, TÜV Nord found that new gasoline direct injection (GDI)—which are helping carmakers meet strict new CO2 emission standards—actually emit higher levels of particulates than old style engines; up to 1,000 times higher than traditional petrol engines.
They even emit 10 times more particulates than new diesel engines, which by law are already required to come fitted with particulate filters (known as a DPFs on a diesel), to help counter their harmful emissions.

VAG start to fit them in 2017/18

 

[Raywood]

I tend to golong with Camel. It matters not one jot what we do as our emissions levels are minimal in world terms. The problem lies with China, India, USA and a few others. If we reduce our emissions to next to nothing it will still not make any significant difference but it does give us the moral high ground but that is about all.
Our diesel has gone, we have a petrol engine which I am assured will reduce our NOx output but at the cost of more CO2. Still have no idea if I am right or wrong but time may tell.

 

[saint-spoon]

I was reading this article about the current fashion for wood burning stoves earlier.

I agree with what has been said above regarding taxation,a green tax is still a tax and is still there to generate revenue for the government, if they were truly worried about pollution then they would tax the fuel used and not the car using it, they would also sort out public transport so that it was truly affordable and reliable. Scapegoating a group for a problem that has many contributes seems to be the fashionable thing to do in government, especially when it means generating more revenue, and the motorists and smokers seems to be the perpetual losers when it comes to taxation.

P.S. I stopped smoking decades ago but do feel for those that still feel the need to inhale a cocktail of carcinogens from burning leaves.

 

[Dustydog]

.

P.S. I stopped smoking decades ago but do feel for those that still feel the need to inhale a cocktail of carcinogens from burning leaves.

As an ex smoker of many years I freely admit I hate the smell now. Cancer sticks!! But there is hope . The NHS still support "stop smoking clinics" and most times supply the patches etc foc.

 

[JonnyG]

Not read the report by which as the prof mentioned no mention of petrol engines ,so i thought ,in my arrogance i dont need to read amateurish reports written, like everybody is stupid. worse the testing protocols are normally weighted bias... as for the debate or assumption worse mpg means worse Nox one has to start at the beginning where to lower Nox levels one has to make a diesel engine less efficient to begin with.simply lowering combustion temperature via the egr valve make the diesel less efficient but reduces NOX . why they haven't gone with a 6% water mix into diesel fuel is beyond me,it lowers Nox keeps the diesel engine working more efficient and cleaner inside!..now dont get me starter on the newer generation of petrol engines like the ford 1 litre petrol engine that chucking out Nox like its going out of business .......

 

[Dustydog]

Jonny
For years I towed with petrol engines. No problems. However as caravans got heavier and diesels more economic in 4x4 since 2002 heavy oil has ruled the roost. Also HMG encouraged me in that direction.
In truth I doubt whatever I drive will make one iota of difference to the atmosphere.

 

[ProfJohnL]

I don't see anyone disputing the issue that pollution levels especially in cities and towns are a health hazard. This on its own is reason enough to try to do something about it. It's a local issue and something that we can each play a part in reducing.

What we personally do may not make a big impact on the international issue, but collectively each small reduction we make does help, and when a nation or even a collection of partner nations can demonstrate that it is capable of making real cut in emissions, it increases the pressure on other nations to try for the same.

Leading can be difficult step, but it's far more satisfying than following.

 

[JonnyG]

hi prof.. why not put the blame where it should be equally ? log burners, industry and car pollution in that order .note in china they have a insignificant diesel market but take a look at their smog and poor air qualities so why is diesel always the main target? worse when they actually do tests on petrol cars the bright wigs have a starting postion of warmed up engines, why?is it because petrol engines have far higher pollutant levels when cold? something diesel engines suffer from far less and given a large percentage of car journeys in cities are done with cold engines surely one should be looking at this far closer?
.To lead one has to be brave and put the blame where it should be.and diesel cars have far less blame than the so called "to lead" brigade would have you believe .now a dumb ass like me its as obvious as high fat milks butter ,cheese, meat ,fats are all ok for our health in moderation but to the so called leaders who over the decades have listened to one so called expert ,one so called study and they come up with a bright idea that this is bad and this is good and tell us so until a decade or 2 later there are newer studies newer results and all of a sudden its "sorry we got it wrong,, For the last decade log burners have been on the rise no doubt due to our economy,some how people believe burning wood is OK but like everything in moderation it may well be but wood burning fires as you know are not OK when 1000s of tonnes of crap wood is being burnt yearly in cities like London especially over the last decade .surprise surprise it just so happens it corresponds with the raise in poor air quality crisis in major cities.. diesel fuels not good ,nor is petrol or wood burners or indeed lots of placements of heavy industries in built up areas. so why target just diesels???

 

[camel]

hi prof.. why not put the blame where it should be equally ? log burners, industry and car pollution in that order .note in china they have a insignificant diesel market but take a look at their smog and poor air qualities so why is diesel always the main target? worse when they actually do tests on petrol cars the bright wigs have a starting postion of warmed up engines, why?is it because petrol engines have far higher pollutant levels when cold? something diesel engines suffer from far less and given a large percentage of car journeys in cities are done with cold engines surely one should be looking at this far closer?
.To lead one has to be brave and put the blame where it should be.and diesel cars have far less blame than the so called "to lead" brigade would have you believe .now a dumb ass like me its as obvious as high fat milks butter ,cheese, meat ,fats are all ok for our health in moderation but to the so called leaders who over the decades have listened to one so called expert ,one so called study and they come up with a bright idea that this is bad and this is good and tell us so until a decade or 2 later there are newer studies newer results and all of a sudden its "sorry we got it wrong,, For the last decade log burners have been on the rise no doubt due to our economy,some how people believe burning wood is OK but like everything in moderation it may well be but wood burning fires as you know are not OK when 1000s of tonnes of crap wood is being burnt yearly in cities like London especially over the last decade .surprise surprise it just so happens it corresponds with the raise in poor air quality crisis in major cities.. diesel fuels not good ,nor is petrol or wood burners or indeed lots of placements of heavy industries in built up areas. so why target just diesels???

Well said

 

[ProfJohnL]

Hello Johnny and Camel.

Please do not twist what I have posted.

I have not accused diesel engines as being the major worldwide polluter, in fact I have not apportioned blame to any singular source, so don't start telling me to point the finger.

However every person who burns fuel is a polluter in some form. On that basis, if everyone who burns fuel of any type take the opportunity to reduce emissions, then the finite amount of worldwide pollution will fall.

My OP comment was about a report (Not of my writing) that looked at the relative production of NOx from a range of Diesel car manufacturers. It was the surprising revelation that the production of NOx is not clearly related to fuel consumption, that peeked my interest and comment.

 

[Dodger524]

Thanks for pointing out my error as Euro 6 & 7 engine regulations. Whilst 6 does exist 7 is still being worked on however they both seem to be intended for heavy diesel engines.
I was interested to read an article recently on Swiss air quality where it seems that wood burning is causing severe problems in some valleys.
I think that we have to accept that we, the human race are polluters and do our best to reduce it.

 

[JonnyG]

Hello Johnny and Camel.

Please do not twist what I have posted.

I have not accused diesel engines as being the major worldwide polluter, in fact I have not apportioned blame to any singular source, so don't start telling me to point the finger.

However every person who burns fuel is a polluter in some form. On that basis, if everyone who burns fuel of any type take the opportunity to reduce emissions, then the finite amount of worldwide pollution will fall.

My OP comment was about a report (Not of my writing) that looked at the relative production of NOx from a range of Diesel car manufacturers. It was the surprising revelation that the production of NOx is not clearly related to fuel consumption, that peeked my interest and comment.

Hi prof, i made no attempt to twist your words , merely miffed at your link ... Diesel pollution as a topic is always being brought up by the media and then the word is spread ala your link but how as a topic with regard pollution can it be properly fathomed,, understood or put into context, when other high NOX pollutants are not scrutinized at the same time for a proper comparison.. All it is is propaganda as yet i have not been able to find a decent report that show exactly what proportion of NOX is actually down to Diesel cars compared to petrol cars compared to say wood burners ect ect ...If indeed we are all to do our bit then surely we should know who exactly should be doing it.. the link as always singles out diesel as a high NOX polluter, which possibly is true .I say possibly because without proper data of other high NOX polluters how can you know how the order of highest NOX polluters lays