Euro6 diesels - better for the planet that petrols?

[Jag_NE]

Trying to summarise a theory that came to mind when posting on another thread and thinking about why we should or should not demonise modern diesels.

The key exhaust nasties (NOx and PM) on a Euro6 (c,2014+) vehicle are virtually identical, NOx is 0.06 for petrol and 0.08 on diesel (g/km), PM is the same for diesel and petrol. Both are small fractions of what they were 15 years earlier.

key thoughts:

1. 1 - Diesels typically use a lot less fuel than equivalent petrols and as they are used by the people who tend to accumulate the larger share of the nations mileage, net CO2 across the vehicle population per mile is far lower for diesel than for petrol.
2. 2 - Smaller petrol engines (think 1.5T petrols vs "equivalent" 2.0 TD) work harder per mile, more revolutions per minute, can they be expected to last as long, on average? As a large amount of pollution is attributable to a vehicles manufacturing and scrapping processes, the longer a vehicle stays in service the better.
3. 3 - Petrol hybrids bring better MPG into the equation but the environmental piece regarding battery supply and disposal. Are Euro6 diesels net better as for the people doing lots of miles (and making up the biggest proportion of the national total) I would still expect a diesel to outperform a hybrid equivalent.
4. 4 - As a caveat I cant see past full EV as being the long term solution subject to infrastructure and renewables being well managed.

To summarise, I don't see the fuss over diesel as long as its in the context of Euro6. We either demonise all hydrocarbon cars and push on with full EV or we get a grip and realise that the latest tech makes for pretty clean cars across the board.

Interested to see who may agree and who may flame me!!!

[Jag_NE]

Magic919 said:

Look at the ‘real world’ testing that is being introduced.

link?

[Jag_NE]

Ninja59 said:

http://equaindex.com is a good source of independent real world testing.

In fairness many of the latest MY17 cars usually are close to it. But I would say looking at it diesels in many cases still fall some way from reality where petrols seem more constant with being closer to the actual ratings.

I have said before though like the OP that to class a petrol as cleaner purely from a particulates perspective is a load of bo**cks the moment it has direct injection as it will produce particulates. Sadly this is something that has until very recently been quietly disregarded.

In some way reverse mentality for a moment a diesel purely focusing on particulates will probably be less dangerous than a DI petrol. Most modern diesels really are only effective over longer distances. Particulate petrols have been increasing in recent years as well so it is not all clean as some would like.

Reality is none of the current personal transport solutions irrespective of fuel can really be "clean". Furthermore, in some part you simply move the problem to a different location (and some of that is influenced by the methods used to create say electricity, which in the UK is in someway not as "green" as other developed nations relying on other methods). Additionally in some cases the raw materials are harder to extract and more dangerous.

Thanks, good points.

[Jag_NE]

Willy Nilly said:

I wouldn't mind betting they end up being a massive pain in the arse.

a bit like DI turbocharged petrols?

[Jag_NE]

thelawnet1 said:

Jag_NE said:

Trying to summarise a theory that came to mind when posting on another thread and thinking about why we should or should not demonise modern diesels.

The key exhaust nasties (NOx and PM) on a Euro6 (c,2014+) vehicle are virtually identical, NOx is 0.06 for petrol and 0.08 on diesel (g/km), PM is the same for diesel and petrol. Both are small fractions of what they were 15 years earlier.

The average in the real world is actually 0.5g/km for diesel for NOx.

https://www.fleetnews.co.uk/news/fleet-industry-ne...

This is because the EU test cycle is useless and the manufacturers cheat. They (not all manufacturers, perhaps, but many) don't care if they are poisoning people, they just care about passing the arbitrary test.

They could make much lower emitting cars, and some do. But they don't HAVE to (yet), so they'd rather gas people to death.

The decision by a manufacturer to release cars that in the real world emit far more NOx than allowed, could be linked to a certain number of deaths (based on excess deaths as a result of pollution). So one could argue that those involved have blood on their hands

Jag_NE said:

key thoughts:

1. 1 - Diesels typically use a lot less fuel than equivalent petrols and as they are used by the people who tend to accumulate the larger share of the nations mileage, net CO2 across the vehicle population per mile is far lower for diesel than for petrol.

Co2 is harmless at the point of emission. Global accumulation of CO2 is harmful, but whereas NOx from UK vehicles certainly kills people, there are no deaths directly attributable to UK CO2.

Jag_NE said:

1. 2 - Smaller petrol engines (think 1.5T petrols vs "equivalent" 2.0 TD) work harder per mile, more revolutions per minute, can they be expected to last as long, on average? As a large amount of pollution is attributable to a vehicles manufacturing and scrapping processes, the longer a vehicle stays in service the better.

This is conjecture. Diesel cars have a reputation for premature failure. In reality most UK vehicles will be scrapped not because of engine failure but simply because the market value is less than the cost of repair. In other words there is an oversupply of new vehicles for economic reasons and because of high labour costs. If we lived in Romania, perhaps we could pay more regard to the real lifespan of the vehicle (as opposed to the UK - it's old and needs 4 new tyres, let's scrap it). But we don't, so this is barely relevant.

I do however believe that petrol cars are lighter than diesel, and use less material. In a throwaway culture, it makes sense to use smaller engines, not long life ones that will be scrapped long before they have actually perished.

Jag_NE said:

1. 3 - Petrol hybrids bring better MPG into the equation but the environmental piece regarding battery supply and disposal. Are Euro6 diesels net better as for the people doing lots of miles (and making up the biggest proportion of the national total) I would still expect a diesel to outperform a hybrid equivalent.

More conjecture.

A quick Google search suggests that the energy cost of making the car is small relative to that burned by the vehicle. The impact of supply and disposal is an entirely different question, but there is no obvious reason why we shouldn't be able to properly recycle/dispose of car batteries.

Also there are diesel hybrids.

You are proficient at calling out others application of conjecture and overlooking your own.

To the CO2 point, because there have been no deaths attributable to rising CO2 levels at the point of emission that makes it less of an issue than NOx? I think rising sea levels and melting polar ice caps present far more catastrophic potential to mankind than NOx from Euro6 vehicles.

Diesel cars have a reputation for premature failure....this is when people buy them for inappropriate duty cycles.Euro6 DI turbo petrols are starting to carry a lot of similar hardware to diesel. They will form their own "reputation" as the vehicle population grows. Older petrols were simple while diesel was implementing all the new tech over the last 15 years.

Drawing a conclusion from a quick google search is a spot on definition of conjecture, well done!

[Jag_NE]

Some Guy said:

Last week, I drove a Outlander PHEV for 700 miles, it averaged 26MPG and needed filling up every 200 miles. This week I had a BMW 335D and averaged 39 MPG and did over 500 miles on a tankful.

That’s the sort of thing I’m thinking about. A state of the art hybrid chucking out 50% more CO2 than a rocket ship diesel....what about the icebergs?

[Jag_NE]

Some Guy said:

Last week, I drove a Outlander PHEV for 700 miles, it averaged 26MPG and needed filling up every 200 miles. This week I had a BMW 335D and averaged 39 MPG and did over 500 miles on a tankful.

That’s the sort of thing I’m thinking about. A state of the art hybrid chucking out 50% more CO2 than a rocket ship diesel....what about the icebergs?