"for no logical reason diesel is 5p or nearly 23p per gallon dearer than petrol"
Blame a Mr Brown: 3p is tax.
madf
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"for no logical reason diesel is 5p or nearly 23p per gallon dearer than petrol" Blame a Mr Brown: 3p is tax.
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As much as I love slagging off Brown, in this case it just isn't true. The fuel duty on unledade 95 octane and diesel is exactly the same the last time I looked, it is the oil companies we should be blaming.
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How do you get such a good low end torque from petrol engines?
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Why does everyone go on about 'low end torque' - use the gearbox. A decent petrol engine has a wider powerband, rev range and is more flexible than a Diesel - provided you use the gearbox properly.
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I'll admit to being hopeless when driving a petrol car, over-revving and then stalling!!!
I just like being able to cruise on the motorway in 6th and not have to worry about changing down to overtake
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These debates over diesel seem to have 1 focus - diesel cars only being useful for long distance drivers and cheaper over these distances.
Does that really have to be the foundation of this debate.
People might buy diesel just because they like they way they drive, even if they only do 15k a year. It doesn't always have to be about the money - its what you like driving.
Edited by OldSkoOL on 01/01/2008 at 20:03
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Well said, OldSkoOl, if we left every decision down to how much it costs and how much bother it is, then we'd all probably still be living in caves!
My old Xantia HDi has been a constant moneypit, and still doesn't quite perform right after a good four figure sum spent chasing vague turbo-related faults. And I only do a very average 12k miles a year now, so am probably just under the threshold for economic viability of a diesel anyways.
But goodness me, getting into it and starting up the oily lump is like putting on a favourite jacket, and I'll keep it till it dies - I like hearing my engines, I like feeling my engines, I lust after arcane old school diesels in the classics section of a certain auction site.
Why? I'm not sure I have the faintest idea, I'll probably stick with and tinker with Rudolf's engines till the internal combustion engine is taxed out of my financial reach!
And anyways, all this gubbins they're adding to petrol engines these days is just gonna make them as complicated, expensive and hard to diagnose as any common rail diesel... Suddenly, that nice looking Pug 205 diesel with its naturally-aspirated, indirect-injection XUD engine that was on that auction site last week looks like a very prudent buy!
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Old Skool has it right.
We (SWMBO and I) both run diesels for short journeys plus the occasional long ones.
Reason is simple: Ever drive a petrol car an average journey length of 1.2 miles every year?
If you have, you will become familiar with : overfuelling, carbonned up valves, high fuel consumption and rusting exhausts..etc.
With a diesel none of the above.
madf
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Why does everyone go on about 'low end torque' - use the gearbox.
Agreed, but with huge torque available, a diesel car often can be driven almost like an automatic in town :)
And I'm not sure of petrol engines that can match almost flat torque curves of many diesel ones.
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Try pulling a heavy trailer utilising the torque multiplication of the gearbox in conjunction with a petrol engine. Once you've done it with a decent turbocharged diesel, you would never ever consider using a petrol engine again, even if fuel consumption didn't enter into the cost considerations.
I would agree with you, madf, that the diesel in older encarnations is absolutely fine for a mixed running regime, which is how I run my Cat III. They also don't throw out unburnt fuel when cold.
However, to return to the subject of the thread, Cat IV diesels and beyond have shown a marked tendency to give DPF problems when operated primarily on short runs. This, together with the added complexity and maintenance overhead leads me to agree with the implied view in the header - the honeymoon is over.
I'm afraid this is another instance where politicians will have killed off the most efficient prime mover for wheeled transport. So much for limiting CO2 emissions.
659.
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Edit timed out, further comment:
The reason a petrol engine with its torque multipled by the use of a lower gear ratio loses out to the diesel is that the usable torque band range reduces in direct proportion to the degree of multiplication achieved by lowering the ratio - this is what gearboxes do. A 3 litre petrol engine will pull my 1500kg trailer up a hill in second gear just as well as my diesel does in third or fourth, but it runs out of steam so quickly as to be pretty useless. In this situation, a ratio change will cause the loss of valuable momentum.
Unhitched on a level road, the differences are less marked, but the increased flexibility of the diesel makes it (for me) a far more relaxing drive. The savings in fuel knock the argument completely into the hat.
The notion of a Cat IV (and beyond) diesel burning extra fuel to clear the soot out of its DPF is to me at least, anathema to any real commitment to the lowering of carbon emissions per unit transportation task.
659.
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I've driven all kinds of vehicles, including big trucks, and for quite a few years a breakdown truck - Diesel of course. For towing they are good. For small-medium cars I an not a Diesel fan. They are good for cruising, but not for entertaing driving on a winding road, nor in town.
I use rental cars a lot for business travel and often request a Vectra 1.9D. They are great for fast and quiet long distance cruising with good economy - hence the preference. However not so nice in town. Not much much happens until the turbo kicks in, then there is a sudden surge of power, then it 'brick walls' at 4500. Definitely not to my taste. Give me a sweet petrol engine anyday for that kind of driving and TBH I can't see myself ever buying a Diesel car for my own use unless I take up towing a caravan (God forbid!). My mate who fixes Diesels for a living runs a Legacy as his own private car...
In terms of emissions the problem of Diesel particulates has been a concern for decades and to some extent Diesel engines have been living on 'borrowed time' for a while now. In the US there is huge concern over particulates and their impact on agricultural workers, truck & bus drivers etc. There is even a plan to get rid of Diesel engines in US school busses because of the worry of children breathing in a lot of particulates. Anyone who has worked around Diesel engines in a workshop for a long time will know how the fumes get into your lungs and 'stick' there. You can taste the soot for days afterwards and every time you cough.
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Thanks for your comments, Aprilia. There is bound to be a degree of subjective preference in the choice of prime mover, obviously coloured by the type of use to which it is being put. The main point of my first paragraph in the last of my posts is that lowering the gear ratio between prime mover and the load is definitely not a substitute for the wider low speed torque range of the diesel. I have to say that town running with a reasonable turbocharged diesel (variable geometry helps to achieve usable boost at lower engine speeds) is no problem for me.
Nobody can argue that particulates are an undesirable form of pollution. The problem is political meddling. Just as the catalytic converter 20 years ago committed all petrol engine users to burn their fuel stochiometrically, wasting millions of tons of hydrocarbons in the process, we now have the repeat situation of the particulates legislation being drafted in a form which requires the use of a DPF - with all its attendant problems. The consequent waste of fuel caused by this choice of technology is criminal.
There are other ways to limit particulate emissions without the use of soot filters, but they require time to develop. The legislators need a quick fix for political gain. I'm afraid that we have cocked it up again for just the same reasons as before. Burning fuel stochiometrically or using it to burn off soot is a crime.
659.
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"You can taste the soot for days afterwards and every time you cough"
Which, in my view, is a good indicator of its toxicity. It's bad enough just riding behind the things on a bike...
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Turbo-diesels with flat torque "curves" are usually obtained by limiting the engine output electronically to reduce stress on the transmission. The natural torque curve would be the exact opposite, a very pronounced peak.
Many petrol engines have naturally flat torque curves, over 90% of maximum torque throughout a wide range of revs.
Turbo-diesels do, of course, have much more torque to start with than non-turbo petrols.
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"There are other ways to limit particulate emissions without the use of soot filters, but they require time to develop. The legislators need a quick fix for political gain. I'm afraid that we have cocked it up again for just the same reasons as before. Burning fuel stochiometrically or using it to burn off soot is a crime."
Sorry, I know knocking of politicians is popular and easy to do, but I think they have it about right.
Over the last few decades car makers around the world have shown that they will not voluntarily introduce emission reducation technologies on a large scale. They have needed legislation - this goes right back to the US Clean Air Ac, the CARB and the 'Muskie Laws' of the late '60's and early 1970's.
Manufacturers have had a couple of decades to work on Diesel particulates but have invested very little effort or money into this research. The Euro-V regs specify PM emission limits but NOT the kind of technology used to achieve the limit - although DPF are going to be the only viable way at present. There is nothing to stop other technologies being used as they become available.
The amount of extra fuel used to regenerate a DPF is very small indeed. A proper DPF system should not use additional fuel during normal running - some of the stuff one the market at present (like the problematic VAG 2.0 systems) is just not properly developed. The problem comes in the complexity of the dosing system etc which is needed.
Petrol engine emissions legislation does not require that there be stoichiometric running - the EU have always allowed for lean burn in the implementation of the regs - you might remember the Carina-E from years back? Don't forget the recent VAG FSI, Mitsi GDI systems etc. etc which are all allowed for in the regs. Incidentally, Euro-V for petrol engines specifically covers PM emissions for lean-burn, which is one of the drawbacks of this technology.
At the end of the day someone has to make a decision about what emission legislation will be introduced and that 'someone' is the 'politicians'. Its naive to think that the industry would simply take it upon itself to reduce emissions and then magically come up with efficient low-emissions technologies. The panels and committees that draft the Euro legislation are stuffed with industry reps - they probably have more influence than they should (and certainly more than they'd have in the US, which has been much tougher on its industry than Europe ever has).
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"Why does everyone go on about 'low end torque' - use the gearbox"
.... or a decent autobox
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Honeymoon? What honeymoon?
I have owned two diesels. A Fabia VRS and a Mondeo TDCI.
The Fabia VRS was bought on the strength of good road test reviews. Possibly a mistake because I didn't like it as much as the magazine road testers did. It felt nose-heavy and had a hard ride and rubbery/dead steering. I will not trust a magazine road test again. Not a patch on an old 206GTI I once owned.
We needed more space and so bought a Mondeo TDCI. That has proved to be a complete basket case of incompatible technologies, made by a company who wash their hands of their cars as soon as you drive away from the dealer. It has had numerous faults and now its finally been repaired it will be sold. Fingers crossed it keeps running until I can p/x it.
I have never had much go wrong with petrol cars so my future cars will be petrol.
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In France they buy many more diesel cars than petrol. I wonder if they have the same problems as us.
Of course you don't see many Ford cars in France.
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The balance between diesel and petrol cars in most European countries is determined by the price difference between the cars and the price difference between the fuels.
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Forgive me, it's probably been covered a squillion times elsewhere. But every time I read one of these threads which alludes to this seemingly widespread habit of misfuelling I just wonder how dozy you would have to be to do this ? I fill up my car with diesel every other day and have done for years and years. I also fill up my wife's car approx. once a week with petrol. I have never even picked up the wrong pump either in this country or abroad, still less attempted to use it ! I do not claim anything other than standard issue synapse connection but it really doesn't seem terribly difficult particularly when the contents of the pump are identified in writing and usually colour coded. If the eyesight standard for driving is set by reading a distant number plate then reading the signage on a petrol / diesel pump at three feet shouldn't be beyond the capabilities of any driver should it ?
As for the suggestion that modern diesels are economic time bombs. It also pays to remember the rules of selective perception. A small number of dissatisfied people will make more noise than a large number of satisfied ones.
My last 1/4 of a million miles have been covered in common rail diesels without one related reliability issue ( most of them Ford TDCI's by the way )
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Honeymoon? What honeymoon?
Quite. In over 25 years of car ownership I've never once owned a diesel.
In that respect, I've never even had a one night stand!
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I've never been the honeymoon diesel driver (though I did go on honeymoon in a diesel). I drive a XM 2.5 TD where as the war office has a little Polo 1.4 petrol. It makes quite a change to drive her car, high revving, smooth and gutless but fun! I only drive 4 miles to work but I use a mixture of bio diesel and straight veg oil so the price is OK.
As for towing with a diesel, I towed a XM on a trailer with a Xantia HDi110 and still got 40mpg overall.
Personal choice as ever. I'm not the kind of person to choose a brand or type hence my regular swapping between AMD/Intel/Ati/Nvidia.
Steve.
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XM 2.5TD VSX S2 Estate.
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Back in 1988 when I was up and down the UK in a Citroen BX17 diesel and thrilled with it's engine and suspension, we were on the M25 going past Heathrow and a BMW525 lost control on the outside lane, came on to the front of the bonnet doing huge damage. He ripped off the fuel lines and the front end was awash with diesel. The police and then the breakdown truck driver both said we would have been fried to a crisp in a petrol car with that kind of damage.
Ever since, I've driven diesel cars on the basis of enhanced safety in the event of accidents. Is this still something to be born in mind when choosing one's vehicle today?
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I'm not sure. Diesels seem to polarise people, you either love or loathe them. There appears little in between. I was thinking about going back to petrol next time as I do well under 10000 miles a year now. But I've been using a petrol Megane 1.6 VVT and although on paper it offers similar performance, you have to wring its neck far more than on the dCi. Diesels offer effortless cruising.
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Diesels seem to polarise people you either love or loathe them. similar performance you have to wringits neck far more than on the dCi.
Agree with that statement, and 25 years ago it was just the opposite, with powerful petrols, and robust, simple diesels that wouldn't pull you're hat off.
Personally i don't like the power delivery of many modern diesels, with a very small power band, which calls for lots of quick gearchanges to make any progress, plus with the very considerable power once on stream, means the FWD diesel makes a see saw kangaroo of acceleration, horrible for passengers.
I have been using diesels a long time now, but i too don't like the way things are going for diesel, and if the hilux had been available in petrol through Toyota GB, i would have had one instead and had lpg fitted with the cost saved.
Naturally we all want different things from our vehicles, and thats why we choose different specs when we buy.
To me reliability is the absolute, and only time will tell if i made the right choice, that choice isn't quite so simple now in the petrol/diesel decision.
So different even to 25 years ago.
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Maybe for the niche group on this forum but not for the country as a whole
news.bbc.co.uk/1/hi/business/7174856.stm
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Autobild in Germany have taken 60 new cars in both diesel and petrol form given them a proper test equivelent to 4 years above average use and in all cases the petrol came out cheapest to run and thats in a country where diesel is cheaper than petrol.Having run diesels for the last two years I have now reverted to petrol they are so much simpler.
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Can we have some facts?
The constant reports of poor reliability for modern diesels on this site can surely be checked by reference to any car breakdown organisation or warranty company. They may not make the facts public but surely there are people clever enough to prise them out?
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"Having run diesels for the last two years I have now reverted to petrol they are so much simpler"
Subjective I know, (but no more subjective than some other views) but I have run diesels for the last 20 years and apart from cambelts every 70 - 80 k the biggest job has been the replacement of about 6 glowplugs on a total of 6 different engines over more than half a million miles (and half those miles done on HDis, other half on XUDs). Can't get much simpler than that - especially since I did the glowplugs myself - about £60 quids worth. All these cars have done a minimum of 45 mpg overall.
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Having been driving for 7 and a half years and having only owned 2 cars, both Peugeot XUD diesels (309 and 306), I've yet to experience owning a petrol car or even a common rail diesel car. When my venerable 14 year old 213k 306TD gives up the ghost I'm still determined to stick with diesel, unless it gets to the point where the price of diesel becomes something ridiculous like 12p per litre more than petrol, then I maybe persuaded to go for a petrol, something along the lines of a 1.6 Ford Focus.
Martin
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I replaced an Astra Coupe with an Astra'sporthatch' last year
I liked the look of the car so the hunt began.
After a few weeks of looking , the only ones in my budget were either the painfully slow 1.4 petrol or the diesel. Both cars were the same age and money, the diesel had 1500 more miles and was a much better drive so that's what I went for.
A year on I am loving it and hope that I won't regret it, plan to keep for about 3 years so plenty of time for expense to rear it's ugly head.
I do approx 11k a year of fast A roads and motorway and am getting early 50s economy so am reasonably happy. The type of driving I do seems to suit the oil burner and I still smile at the torque after a few years of revvy petrols.
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The only diesel I've owned was an Audi A4 Tdi (115bhp). It gave good service - never breaking down and returned an average of 51.4 mpg. Performance was very respectable and completely linear - none of the current surging between gearshifts. The only downfall was the exhorbitant servicing costs - even 2 independent specialists were MORE expensive than the Audi dealer ! But even with diesel being dearer at the pumps, it's still THE choice for higher mileage users. I only do 10k a year and have a 1.6 petrol at the moment, but as quite a few of those miles are local (less than 30 mile trips) I'm looking at another turbo-diesel. I also like the torque-heavy midrange compared to small capacity petrol engines.
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