Petrol vs Diesel - interesting...

[Wattie]

That's cool... I'll just have to overtake in my faster petrol engined car, so that I don't have to smell your fumes :lol: :lol:

 

[Tiptop Topcat]

Just looked at 3-series and the difference is even more marked:

Model OTR Price Fuel BIK (%) CO2 (g/km) Combined fuel consumption (mpg) Power Output (hp) 0-62mph (secs)
325i SE £26,585 Petrol 21% (21%) 170 (170) 39.8 (39.8) 218 6.7 (7.1)
330d SE £30,395 Diesel 22% (25%) 160 (175) 46.3 (42.8) 231 6.7 (6.8)

So for exactly the same acceleration you save nearly £4k at purchase, 1% BIK (but on a lower figure) and fuel consumption is just 16% worse (about 1.5p per mile)

I do have a prejudice against diesel, it is really nasty stuff from a health point of view - not just the toxic emissions, but also killing motorcyclists and wildlife through spillages. But what really gets to me is that the almost total switch to diesel is based upon mis-information and misunderstanding.

With regard to hybrids, I agree that in their current form they are not viable as a long term solution to the sustainability issue (but I personally, would still rather that than a diesel). However, it is almost certain that future sustainable cars will drive the wheels via electric motors and a hybrid is the first step towards developing that technology - you then just need to find an alternative power/battery charge source to the existing petrol engine.

Sorry Wattie, I know this seems like a game of tennis but this is not apples with apples. When we have assessed various cars, the 320D, not 330D delivered the same performance as the 325i at less cost. It was far cheaper in terms of BIK.

And I don't believe that given the dramatic change in buying habits, the general public and fleet managers in particular can be as badly informed as you suggest.

Again, whilst it is odds on that given your job, you are far better informed than I, I cannot help but feel that the health case is being over-stated.

 

[Wattie]

Sorry Wattie, I know this seems like a game of tennis but this is not apples with apples. When we have assessed various cars, the 320D, not 330D delivered the same performance as the 325i at less cost. It was far cheaper in terms of BIK.

Not according to BMW's own figures... 320d is quoted as 7.9 secs to 100kph as opposed to 6.7 for the 325 petrol, and BMW are not usually guilty of under-selling their performance!

The 320d is massively cheaper in terms of BIK though, because they managed to swing it so that the one tested had Stop/Start fitted. What people don't realise though is that stop/start doesn't work if the air-conditioning is in use - so your actual fuel consumption is likely to be far worse than the quoted figure (but if it's company fuel who gives a s**** I guess!)

As I said before, the real problem is that all this time and money invested in developing diesels to cheat the tax system is stifling what we really need - alternative fuel technology for when the oil runs out.

And bio-fuels are not the answer - already the World is starting to complain about rising basic crop prices, as farmers profit from growing for fuel rather than food.

Investing in diesels (and straightforward petrol engines for that matter) is rapidly becoming a bit like re-arranging the deckchairs on the Titanic...

 

[Big Bob]

The area where Diesels score on performance is on torque. Which while the 0-60 times are often beaten by the petrol equivalent, it is the mid range acceleration in top gear that give a diesel the edge on motorway and trunk road manouvering/overtaking.
Yes and thats why they are good in trucks and 4x4s.
The issue I still have for diesel is the emissions of pariculates, which can cause asthma sufferes like my wife issues.
Diesels engines are more expensive to make and that reflects in the price for a diesel to some extent, but the Manufacturers :bandit: have also made hay with the buying public over the illusion that they are cheaper to run and greener :mrgreen:
Of course us petrol heads have to face up to Audi and Peugeots undoubted impacts at Le Mans for the last events :nooo: !
Having said all that I've just bought a Merc V8 ML420 CDI with 7 Speed G Tronic. Very seamless performance as a result of the 7 Speed box, which has wiped the floor with sales of the similarly priced Petrol V8 ML500.
Any way more Big Bob bull****, but another post
Regards

 

[Wattie]

Having said all that I've just bought a Merc V8 ML420 CDI with 7 Speed G Tronic. Very seamless performance as a result of the 7 Speed box, which has wiped the floor with sales of the similarly priced Petrol V8 ML500.
Any way more Big Bob bull****, but another post
Regards

I'll let you off with that one as it's a 4x4 :wink:

But how many of us would buy a diesel 911?

 

[Robertb]

...or to put it another way, when was the last time you made a special effort to hear a diesel accelerate away?

Personally, for a daily-driver I really don't care if its powered by a V12, an electric motor or steam provided it gets me about my business with minimum hassle, quietly, quickly if needed, and economically.

But for the 'weekender' its got to be an inspirational power plant, and that means "windows down in a tunnel" sound as much as anything. So far, no diesel does that.

A friend reckons all these high-performance big diesels rather miss the point as a diesel is all about economy- day to day, he thinks a 320d is a much better bet than a 335d as the more power there is, the more the advantage is negated, as demonstrated by Wattie's figures.

 

[Big Bob]

Robertb
You are so right. If its a sportscar it has to have the exhaust note :thumbs: !
I'm glad I'm not the only one who winds the windows down and gives the car a bootfull when going through tunnels and underpasses :lol:

As for a 911 Diesel, well it would have to have large external speakers blasting out a real sports car exhaust sound to compensate. Might bu**er up the aerodynamics though :food:
Regards Big Bob

 

[Wattie]

Again, whilst it is odds on that given your job, you are far better informed than I, I cannot help but feel that the health case is being over-stated.

I used to live in a new apartment development in Lamberhurst and whilst I had a flat at the rear, my friend bought one overlooking the main A21 trunk road (before the village was by-passed).

Despite no history in her family, or previous problem herself, she developed really severe asthma. One day we were playing badminton and she collapsed on court, her lips and eyes blew up like balloons and she went into a comatose state in seconds and was having severe trouble breathing... An ambulance was called and the first aider on site did what he could while we waited, then she spent the next few days on a respirator... If she had been on her own, she would have died.

Her life is changed forever now, she has to carry an inhaler at all times, she cannot do anything remotely energetic when she is alone (she used to enjoy lots of solo walking and horse-riding) and it has been directly attributed to NOx emissions from the diesel trucks that used to thunder up and down past her open windows.

If that doesn't convince you that diesel is really nasty stuff, I don't know what will.

The CO2 issue is still unproven, has no direct impact on human health (in fact I read a scientist's report recently that concluded that the predicted rise in temperature globally will actually suit humans better), yet it is well-proven that NOx and PM are harming people locally right now.

 

[Wattie]

...or to put it another way, when was the last time you made a special effort to hear a diesel accelerate away?

Actually, I have to confess to something here... When we did the Range Rover TDV8 launch training in Spain, a convoy of them had to climb a really steep hill to an old castle for a driver change, and the sound of 20 V8 diesels at full torque climbing the hill, echoing around the valley, was quite impressive - but in a 'Tractor-Pulling' kind of way

A friend reckons all these high-performance big diesels rather miss the point as a diesel is all about economy- day to day, he thinks a 320d is a much better bet than a 335d as the more power there is, the more the advantage is negated, as demonstrated by Wattie's figures.

Absolutely: IMO there are only two possible justifications for a diesel engine:

1.) To absolutely minimise the amount of fuel used (but there are still petrol engines that are just as good, if not better, at this)

2.) When you need lots of torque at low engine revs: i.e. Serious off-roading or towing heavy trailers (and I don't mean piddling little caravans here - I mean several tonnes) i.e. TRUCKS!

I too wind my windows down in tunnels (I have a video of me driving the 996 round the circuit at Monaco), but I'm afraid we are going to have to sacrifice something in the future if we want to keep buying new supercars: I for one, would rather give up the noise than the performance and handling...

 

[LOJO]

A couple of years ago I was told you have to do over 15k miles pa otherwise it is cheaper to by a petrol, since then the price difference has vanished, so it is probably much more mileage now!

One benefit of deisel is that you only have to stop for juice every two weeks instead of every week!!

But when I needed more space and replaced my 320d it was with an Audi A4 2.0 FSI - smoother, nicer to drive, more power and less torque and several grand cheaper than an Audi 2.0 diesel.

LJ

 

[911UK]

to add some info to this debate...

One group will insist that petrol is far better, largely because petrol cars are faster, quieter and cheaper. Diesel fans will, of course, highlight the vastly better fuel consumption plus the improved torque from a diesel engine, which gives good pulling power and less gear changing, making driving in everyday, rather than race-track, conditions a pleasant experience. There are also the muddy waters of exhaust emissions, with strong arguments on both sides of the fence.

So what is the objective truth? Diesel engines inherently use less fuel than petrol cars, and so will undoubtedly save you money in the long run. This is particularly true in town driving, if you make a lot of short runs, or if you do towing, where the differences are even more marked. On long trips at motorway speeds the differential closes. Diesel fuel in the UK is usually priced close to unleaded petrol, so figure out the difference in hard figures comes down to a straight MPG comparison. However, if you travel a lot through France, you'll find that diesel is approximately two-thirds the price of petrol, enhancing the savings even further.

There is also a commonly held belief that diesel engines will run for much higher distances than petrol engines before giving any trouble. Whether this is actually true of today's sophisticated engines is arguable, but a consequence of it is that there is a keen market for diesels that have covered more than 75,000 miles than for similar petrol-engined cars. It means that if you are a high mileage driver, a diesel car will be easier to sell when the time comes, than a petrol version.

There are disadvantages to owning a diesel car too. One is the noise, which despite many advances in recent years, is always louder when starting from cold and is certain to be noticed by all your neighbours on a winter's morning. A related problem is vibration - rarely a real problem today, but always more noticeable on cold starting than with an equivalent petrol engine.

 

[fake]

Petrol v Diesel

Try the following searches:

(Car maker name) turbo failure.

Almost all are EGR valve failure in diesels which lead to expensive repairs, ultimately the turbo fails and the car runs on its own engine oil, (sucked through the turbo oil seals) then the sump goes dry. This trick is exclusive to diesels.

The very high injection pressures (1600 BAR!) have the effect of hydo plasma erosion on the injectors, this changes the injector pattern (at about 70/80 000 miles) which can wash the oil off the bores and lead to accelerated bore wear.

Like Wattie, I prefer Petrol - shaken not stirred

 

[Big Bob]

Good stuff Fake very interesting.
I was intially a bit worried about taking your post seriously in view of your "alias" :finger: . However as Big Bob does not mean I'm a fat bast*** :nooo: , then thanks for the info, because it makes sense to my experience ld:
Regards Big Bob.

 

[smallspeed]

i was having this discussion with a friend recently; he has just brought an alpina b3 biturbo (based on the new BMW 335i) and is getting around 29 mpg from it.. while thats not as groundbreaking as the 70+ my mum gets from her smart car, its M3 quick (if not quicker in the real world) and I don't think there's a diesel that would touch it..

BMW have always been good at producing efficient engines, and in a way their latest crop of twin turbo sixes almost eliminates the need for a high performance diesel.. The Alpina replaced a 650iSE which got around 25-27mpg over the course of the year or so that he ran it.. 635d anyone?!.. :floor:

 

[Big Bob]

while thats not as groundbreaking as the 70+ my mum gets from her smart car, its M3 quick (if not quicker in the real world) and I don't think there's a diesel that would touch it..

Now I have to agree, my Smartie runs about 115-120BHP and is quick and nimble, but still does over 50mpg :thumbs:
Big Bob