I saw this article in my local paper and I thought the ?Back Room Boys? would be interested:

? Leaps forward in car engine and fuel technology have been so successful in reducing exhaust emissions that 100 modern cars now produce less hydrocarbons than one petrol lawnmower.
According to a government index of vehicle emissions, small two-stroke engines of 50cc or more are rated 74 for carbon monoxide and 338 for smog-inducing hydrocarbons. Cars which meet Euro III emissions standards ,(such as the latest Fiesta or Rover 45), rate just 7 for carbon monoxide and 3 for hydrocarbons.

Buses, lorries, and taxis stand out as the major contributors to urban motor vehicle pollution. An older articulated lorry produces as much particulates as 350 new petrol cars and the nitrogen oxide of 284 new petrol cars.

The current generation of petrol cars produces around one-sixteenth of the toxic urban pollution of their non-catalytic converter forerunners.?

What do you think?
Re: CAR EMISSIONS - Roger Jones
Confirms what I have always suspected. And, advances in diesel-engine design for cars notwithstanding, there seem to be serious and as yet unpublicized concerns among medical scientists about particulate emissions from any diesel engine, which is worrying in view of the increasing popularity of diesels. I base this on a conversation with one such scientist from what's probably the leading medical school in the UK. No doubt the new engines are far better behaved -- I'd be considering one if I were changing cars -- but the wider issue is worrying.
Re: CAR EMISSIONS - stuart bruce
It is not correct to talk just about diesel engines. Recent research shows that petrol engines also produce particulates, its just that as they are small in size nobody thought of looking for them before.

The rub is that the smaller particulates eg
Some of the engines which produce the most of these fine PM's are modern direct injection petrol engines, and a Peugoet 607 HDi with particle filters was as clean as the cleanest engine, plus lower CO2 to boot.
This sounds like a typical selective use of statistics to prove a particular point, which almost certainly uses laboratory figures. In particular the 100 cars to one lawnmower ratio looks highly suspect. This is based on hydrocarbons, comparing a two-stroke to a four-stroke. By definition two-strokes, being a total loss system, must have higher hydrocarbon emissions, but "lawnmowers" as quoted in the article, use a pre-mix two-stroke mix, typically at a 25 to 1 ratio, whereas, for example, modern motorcycles use an injector system giving a 100 to 1 ratio, higher engine temperatures, cleaner combustion and far lower emissions. Note that the carbon monoxide ratio is ten to one. Other ratios will also be vastly different from "100 to 1".
It is agreed that CO2 is the main greenhouse gas but this is not mentioned, thus giving the false impression that all emissions are in the same 100/1 ratio.
Note also the comparrison of new cars to "older articulated lorry". Why not new car to new lorry.
There is a well-known quote which goes "There are lies; damn lies; and statistics"
Reading between the lines, it sounds like the first shot in a propaganda war to up the tax on two-stroke motorcycles, disregarding the fact that, by nature of their comparatively small size, total emissions are relatively low.
In the real world, cars travelling at high speed on a motorway probably come close to the ideal. In town, where the need is greatest, catalytic converters rarely come up to operating temperature and are made useless by moisture and hydrocarbon deposits.
If you want a demonstration just watch your catalysed car being MOT'd. It usually takes three of four tries, with the engine being thrashed under no-load conditions, to get the readings down to the "pass" level.
In the congestion of London's pathetic road system, a high proportion of an engine's time is spent idling. Comparison of different engines and fuels under those conditions would give very different results.
The choice of catalysts to reduce pollution was a poor one. Lean burn technology produces equivalent results under a wider range of conditions and does not bear the burden of the higher fuel consumption of cats.
Re: CAR EMISSIONS - Adam Going
Oh Dear. I have just got to go and mow my lawn !!
Re: CAR EMISSIONS - Gwyn Parry
I have always felt that deregulation of buses in the 80s led to the widescale recycling of buses meaning that older and very filthy buses roam our city streets in packs. I don't know about anybody else's neck of the woods but around here ancient double deckers cram hoards of children into buses that wouldn't seem out of place in a museum. These buses then become one vehicle
protable enviromental disasters on wheels belching incredible amounts of noxious smoke into the once beautiful fresh air of rural Wales.
Re: CAR EMISSIONS - Charles Renard
I agree with you on the ancient bus as a polluter, Gywn. The de-regulation was a scrappies delight. At one move all his stock of (s)crap PSV's were back on the road with a lick of paint and a private numberplate to hide the age of the old crocks. It is not a problem that is particular to Wales, and it also meant the destruction of the UK bus industry as council orders for new buses dried up in the face of chancers who ran the old wrecks. The position is getting a lot better as the ancient fleets are becoming hard to keep on the road due to the costs of repairs.
Re: CAR EMISSIONS - another interesting fact - Jonathan
There is a little thought of point here too. New cars require building (naturally) which remarkably creates about 100 times the amount of CO2 that a car emits in its lifetime.
The Govt (in its infinite wisdom) is actually promoting the production of CO2 (by bailing out longbridge et al).
By taxing new cars on their CO2 levels at a lower (or different) level than older ones they are creating an unequal and polluting policy. Why not try to improve the efficiency of older cars which have already been produced and therefore add no additional CO2 to the atmosphere than that from the exhausts.
Re: CAR EMISSIONS - another urban myth - Rod
>New cars require building (naturally) which remarkably creates about 100 times the amount of CO2 that a car emits in its lifetime.

Do you have any figures to back that up? I asked a friend (who works for Nissan) to come up with a figure for this and he estimated that building a car produces in total amout as much CO2 as 2.5-3 years use (based on a Micra estimating the energy consumption used to create the various materials by weight).

This is obviously going to vary depending on size, efficiency and materials used but it suggests that to replace an old car with a new one to reduce CO2 production you would need to justify a 20% improvement in fuel consumption.

Of course if you want to base it on toxic exhaust emissions then an old banger will produce more in one years use than a new car will produce in it's lifetime. What was it Disraeli said about statisics?
Re: CAR EMISSIONS - another urban myth - Rod
>Do you have any figures to back that up?

Sorry, that sounded rather accusatory. It was meant as a genuine (friendly) enquiry.
Re: CAR EMISSIONS - another urban myth - Jonathan

Unfortunately I do not have any figures. BUT...

Your friend probably stated the values for building the components. If you include all the CO2 for the components then it can add up to about 10 years. For example

Steel - exploratory surveys, mined, extracted, hauled, processed, refined, hauled again, pressed, (include all the heating of this).
Plastics - oil is one of the major constituents for this - exploratory surveys, drilling, extracting, tanking, processing, refining, refracting, processing, haulage, storage..

Not to mention the CO2 emissions of all the factory workers who make these components and the manufacturers of the machinery what makes the components.

So I really need to go on?

If you are building a completely new car, you should take the whole lifecycle of the materials you are using, this includes cradle to grave.

I will, however, have a look for some statistics to back up my claim. Why don't you have a look also?


PS No offence taken.
Re: CAR EMISSIONS - another urban myth - Rod
I had a couple of searches but couldn't find anything statistical although I had a look under aluminium (as this is a very energy intensive activity) and found a few interesting facts from (which is an industry thing so I'd take it with a pinch of salt):

* producing 1 tonne of aluminium produces 3.7 tonnes equivalent of CO2 (sounds a bit low to me)

* recycling aluminium reduces energy consumption by 95%

* using 1 kg of Aluminium in vehicles saves 20 kg of CO2 during the cars life

Anyway, at a rough guess, if you were to assume that the raw materials used in a vehicle produce 4 times their weight in CO2 to produce and manufacture will double this then a 1250 kg car will produce 10 tonnes of CO2. A typical emmission figure for a petrol car at this weight would be 170 g/km of CO2. Given a lifetime of 200,000 km this would equate to 34 tonnes of CO2 from the fuel consumed.

I don't think you could ever get an accurate figure for these sorts of things because, as you pointed out, there are so many variables (although the 34 tonne figure frightens me!)

I think that the aluminium website does make an important point that it is vitaly important to recycle materials and if any government does want to introduce a scrappage policy then recycling has got to be a major part of this.

Re: CAR EMISSIONS - another urban myth - Jonathan
i agree wholeheartedly
Re: CAR EMISSIONS - Adam Going (Tune-Up Ltd)
Seriously folks,
I have now mowed my lawn, and would point out that many modern petrol mowers are in fact 4 strokes, but that is nit-picking !!

My main grouse on this subject is that Carbon Dioxide emissions, the main contributor to global warming, are considerably higher from petrol engines since catalytic (cataclysmic ??!) converters were forced upon the car manufacturers by the same politicians (I view them as all being the same, regardless of party) who now aim to tax us on the basis of .. guess what .. high Carbon Dioxide emissions. But since when were politicians qualified as engineers or chemists, or even sensible. Answers on a postcard please !!

Happy motoring, Adam.
Re: CAR EMISSIONS - steve paterson
Maggie Thatcher was a qualified chemist. She favoured 'lean burn' technology as the way to reduce emmisions. I suppose the motor industry found it easier and cheaper to go for the 'cat' solution. Use the same old engine technology and stick a filter on the exhaust! Good aftersales as well.

Re: CAR EMISSIONS - Cedric Turner
A couple of years ago In France they offered 600 quid to drivers of older vehicles to change to newer "less polluting" cars, what a way to prop up your motor industry ! Now we are faced with a problem of too many old worthless cars being dumped on our streets, this Govt ought to apply a similar initiaive to get people to drive new cars. the motor industry is a big employer in this country and should be supported. the arguments against building new cars are drivel, new cars are far safer and more reliable than old ones. Ok there are emissions caused by building the car, but this is the price we pay for living in an industrialised nation. We make steel etc and nobody is concerned about the impact on the environment of this, indeed most steel is made from recycled scrap.
Re: CAR EMISSIONS - John Slaughter

One of the big drivers for cats was the 'anti lead' lobby. Because cats are intolerant of lead, they were seen as a quick fix to get rid of lead - but as you say at the expense of higher carbon dioxide emissions, and completely stalling development of any other technology. Typical case of blinkered interest groups totally ignoring the wider picture.

Engines don't need lead - it is actually a problem and was the source of much of the so-called 'coke' that engines used to need removed at regular intervals. It was also the cause of short spark plug life and oil contamination. Unfortunately the cat 'solution' denied us the alternative technologies that could have been the way to improved economy - and as we're dealing with a hydrocarbon fuel, economy benefits immediately translate to reduced carbon dioxide.

Re: CAR EMISSIONS - another urban myth - Cliff Pope
Don't lawnmowers usually do smaller annual mileages than cars?
Surely in all this argument about different emmisions, it ought to be the total volume of undesirable gases emitted per annum that counts, not rate at any given moment of measuring ?
Re: CAR EMISSIONS - Tony Cooper
I am very keen on buying a diesel powered car as I travel a lot in mainland Europe where this fuel is noticably cheaper than petrol.
Has any unbiased scientific minded body or organisation conducted a thorough investigation into the various merits or de-merits of diesel versus petrol.
It is a very emotive subject being linked to cancer producing byproducts and an honest set of data would be appreciated. I have no desire to unneccesarily add to the worlds pollution problem but LPG is not yet a viable option and across Europe on a bike doesn't appeal!
Buy a diesel. Fill it up with Biodiesel on the continent then drive six hundred miles (I kid you not) on your 52 litre tank and have a good hard think about who's doing most harm, you or the two litre petrol engine brigade who manage 350 and think they are doing well. Having done both there is no argument in my view. In town the particulates may be a problem, but then petrol engines make them as well. On the motorway diesel engines are by far the best. And in my experience there are very few people walking along the motorway to breathe in any nasty soot. Those that are will die of other things I think.

When it comes down to it, burning fossil fuels is very silly. We should do it less.
Re: CAR EMISSIONS - Kevin Alder
Lots of unbiased scientific minded bodies have conducted thorough investigations of the type you describe. They've all come up with different answers.

As Chris says, the only way to be sure you are not polluting the atmosphere is to stay at home and eat no greens.
We recently changed from a Fiat Bravo HLX to a Golf GT TDI PD. Both cars have similar horsepower but the diesel seems much more driveable. My wife does her fuel accounts every week, although with the diesel this has now changed to a fortnightly ritual due to the fuel-saving benefits.

I doubt we will buy a petrol car again. Also, as biodiesel will eventually be introduced in the UK, fossil fuels can be properly used for the manufacture of polymer products instead of simply being burned. Biodiesel will also be largely CO2 balanced - it uses up the CO2 it produces on combustion.
Even in town, where the average journey length is, I believe, about five miles, a diesel will be better than petrol because the catalytic converter on the petrol engine will not have reached operating temperature.
The pre-heater glow-plugs on the diesel ensure that the engine is up to working temperature almost from the word go, resulting in cleaner combustion and lower fuel consumption (hence less CO2) than the petrol engine with its choke out doing about 15 miles per gallon.

Value my car