Car running costs - mid-size car - diesel vs petrol.

[Butcher]

If it lowers economy you're using more fuel and ultimately producing more emissions, so yeah pretty pointless. Obviously there's a lot more science and stuff to it, but that's the basis.

More fuel usage means more oil shipped over on boats that measure fuel economy in gallons per mile rather than MPG, or more commonly tons per hour, which in the case of a fuel ship is around 16 tons per hour or just over 5,000 gallons per hour.... and that's just port to port. You then have the HGV tankers delivering fuel to your station at, what, 6.5mpg on average?

Then you have the folk who just implement DPF and EGR deletes anyway...

It's an issue of local vs global pollution. Is adding an extra lets say 10% CO2 to the atmosphere more or less harmful than spewing tons of lead and NOx into town centres? The current thinking is that the CO2 is less of an issue. The whole, "lets just minimise CO2" thinking is what lead us to excessive numbers of diesel cars being used for short urban journeys, which in turn has caused this knee jerk reaction as people have realised that actually local pollution is probably a larger issue when it comes to private cars.

If we run with your line of thinking, would you support the reintroduction of lead to petrol? It would reduce fuel consumption, and thus overall emissions, but at the cost of lead in the air. A small price to pay maybe?

[Ttaskmaster]

Is adding an extra lets say 10% CO2 to the atmosphere more or less harmful than spewing tons of lead and NOx into town centres?

Does it matter?
It's more about how much pollution in general is being kicked out, both in what I use and in what it costs to get me what I use.

people have realised that actually local pollution is probably a larger issue when it comes to private cars.

Yes, so they want to ban cars in cities but let them go gack up the countryside instead... That doesn't solve the problem, that just kills off someone else.
As is, they reckon only 20% of pollution comes from vehicles anyway.

If we run with your line of thinking, would you support the reintroduction of lead to petrol? It would reduce fuel consumption, and thus overall emissions, but at the cost of lead in the air. A small price to pay maybe?

Why not find a way to make existing fuel engines even more efficient, instead? A much smaller price to pay and a far bigger benefit.

[Butcher]

Does it matter?
It's more about how much pollution in general is being kicked out, both in what I use and in what it costs to get me what I use.

Well yes it does matter. Reducing climate change is no good if it significantly increases the number of people in urban areas who are seriously ill from local pollution.
General pollution is fine to worry about, but not at the expense of local pollution.

Yes, so they want to ban cars in cities but let them go gack up the countryside instead... That doesn't solve the problem, that just kills off someone else.
As is, they reckon only 20% of pollution comes from vehicles anyway.

There are fewer people in the countryside, so less are affected. Also the people who are there tend to be further from roads which reduces the impact on them. Not to mention that a lot of journeys are to get to built up areas, people who need to drive to a town centre aren't suddenly going to razz around the countryside just because they can't drive in town.
The stat is that 20% of CO2 comes from vehicles, not 20% of pollution. If you look at NOx levels then the majority comes from vehicles.

Why not find a way to make existing fuel engines even more efficient, instead? A much smaller price to pay and a far bigger benefit.

Because there are limits on how much more efficient they can get. Best case, you might get a 10-20% reduction. Catalytic converters have reduction rates of over 90%. DPFs typically yield an 85% or better reduction. You can't get that level of reduction just from fuel efficiency savings.
I would say that the far bigger benefit just isn't there compared to the actual benefit of not spewing NOx and particulates into town centres.

Besides you didn't answer my question. Adding lead to fuel would make existing engines more efficient. You could increase compression ratios (as fuel would be higher octane) and bin off the catalytic converter. A small price to pay, no?

[Ttaskmaster]

Well yes it does matter. Reducing climate change is no good if it significantly increases the number of people in urban areas who are seriously ill from local pollution.

I presume there are massive factories located at the Poles, spewing out noxious fumes in order to cause holes in the ozone layer, rather than local pollutions being a problem, then?
The larger cannot be caused by the local, no?

There are fewer people in the countryside, so less are affected.

There are too many people in the cities, causing more problems than just pollution with their overcrowding. Kill them and solve several problems at once.

Not to mention that a lot of journeys are to get to built up areas, people who need to drive to a town centre aren't suddenly going to razz around the countryside just because they can't drive in town.

Except that they already are razzing around the countryside, because towns are so full of traffic... and with things like DPFs, you kinda have to go razzing somewhere or it will block and fail. Motorways and other main roads are usually out, again due to traffic and roadworks.

The stat is that 20% of CO2 comes from vehicles, not 20% of pollution. If you look at NOx levels then the majority comes from vehicles.

Ah, so putting a DPF on my car is gonna undo all the damage done by, say, deforestation?
I said pollution. I didn't single out any one particular element, as it all combines to destroy the environment.

Besides you didn't answer my question. Adding lead to fuel would make existing engines more efficient. You could increase compression ratios (as fuel would be higher octane) and bin off the catalytic converter. A small price to pay, no?

At this point, I really don't care. Yes, spew lead out. Kill some people. Whatever serves the point you're trying to make.

[Butcher]

I presume there are massive factories located at the Poles, spewing out noxious fumes in order to cause holes in the ozone layer, rather than local pollutions being a problem, then?
The larger cannot be caused by the local, no?

Factories are usually built away from residential areas yes. Hardly at the poles due to infrastructure, but have you not ever considered why factories are built as far out of town as practical these days?
As for the larger and the local, it depends on the pollutant. NOx is not a global pollutant, it is too short lived in the atmosphere, nor are particulates. But they are harmful to humans, so need controlling at a local level. By saying fuel economy is the only thing that matters you're saying that it doesn't matter how toxic the exhaust is as long as there is a reduction in CO2, regardless of how many people it kills in the mean time.

Except that they already are razzing around the countryside, because towns are so full of traffic... and with things like DPFs, you kinda have to go razzing somewhere or it will block and fail. Motorways and other main roads are usually out, again due to traffic and roadworks.

Still helps reduce the exposure due to population sparseness and proximity to roads in the countryside.

Ah, so putting a DPF on my car is gonna undo all the damage done by, say, deforestation?

We're talking damage limitation here, obviously. Putting a DPF on your car may reduce the number of people getting respiratory illnesses. But I guess as long as you're alright?

I said pollution. I didn't single out any one particular element, as it all combines to destroy the environment.

And yet you used a statistic that is for one particular element. Which is it? You can't have it both ways.

At this point, I really don't care. Yes, spew lead out. Kill some people. Whatever serves the point you're trying to make.

Now you're just making yourself look foolish.

[Ttaskmaster]

Factories are usually built away from residential areas yes. Hardly at the poles due to infrastructure, but have you not ever considered why factories are built as far out of town as practical these days?

Becasue screw the environment, so long as the city folk are still alive to pay their taxes?
I dunno. You tell me......

By saying fuel economy is the only thing that matters you're saying that it doesn't matter how toxic the exhaust is as long as there is a reduction in CO2, regardless of how many people it kills in the mean time.

No, by saying that I'm saying that. It's quite simple and specific.
Reduce the fuel used, you reduce the pollution produced. Filters lessen it, reduction reduces it.

Still helps reduce the exposure due to population sparseness and proximity to roads in the countryside.

Well there are two main roads and a motorway pretty darn close to us here... We probably see more cars (and definitely more HGVs) per day on each of those than I'd see going down the main road past my flat when I lived in central London!
Oh, and there's a major freight line out the back, too...

We're talking damage limitation here, obviously. Putting a DPF on your car may reduce the number of people getting respiratory illnesses. But I guess as long as you're alright?

Well I don't tend to go into the city, so what should I care? You're the one chucking all these cars and their pollution out in the country toward me... So yeah, long as I'm alright!

And yet you used a statistic that is for one particular element. Which is it? You can't have it both ways.

I said pollution. I assume they meant all pollution, which might well happen to also be 20% of one particular element in one particular aspect of whichever particular pollution you care to look at, too... but I took that to mean all the pollution that is of particular concern to people, be it manufacturing, deforestation, or whatever.

Now you're just making yourself look foolish.

And yet my car still runs better without the DPF, though, so...

[Zak33]

Adding lead to fuel would make existing engines more efficient. You could increase compression ratios (as fuel would be higher octane) and bin off the catalytic converter. A small price to pay, no?

lead doesn't increase octane rating.

Some of the chemicals historically used to raise octane rating happened to hold lead (i think it was GM who discovered TEL )... but that's not why lead was used. It happened also that lead helped protect valve seats and so less hard valve seats were needed in cars for a while.. and then as the octane booster that contained ead was taken off the market cars needed either hardened valve seats or a lead additive to protect them. Catalytic convertors die within minutes of leaded petrol being used in them

there are other ways to increase octane rating and thereby increase compression ratio and thereby increase performance and thereby improve fuel efficiency. But they cost more than the gain. Better fuel blended with regular petrol for example. But it's not affordable for the gains in MPG

[peterb]

Adding lead would poison the catalyst and lead to a rapid MoT failure. Catalytic converters (and the harm that heavy metals do to the environment) were the drivers for reducing lead in the first place.

Octane rating is a measure if the ignition temperature, adding lead increases that temperature so technically it does increase the octane rating and therefore the efficiency of engines by enabling higher compression ratios. That was particularly relevant with conventional carburettors. Reduction in Octane ratings by reducing lead drove manufacturers to improve efficiency with various injection system coupled with electronic engine management sensors to give much finer control over the optimum mixture at various loads and engine speed.

[Butcher]

Tetraethyllead was specifically invented as an octane booster. The competition was things like ethanol and similar alcohols. TEL was patentable though so was preferred, and because you only needed a small amount is was very cost effective.

As peterb says, catalytic converters arrears the main driver behind unleaded fuel. Also they're a major driver behind electronic fuel injection as you need to run them at close to stoichiometric to avoid them overheating.