Diesel or Petrol - thirts
I'm sure this has been discussed before, but this isn't about which is the best financially (well it may be a bit)

I prefer diesels over petrol engines, but our milage (about 8k a year) doesn't justify it on cost alone. However that isn't the real issue.

I know that diesels are great for mile munching. How are they in term of longlevity, reliability, maintanance costs for lots of very short journeys. School run, short commute to work, shoppping etc etc.

I'm specifically looking at the Ford 1.6 diesel


Diesel or Petrol - the swiss tony
10 years ago I may have said diesel.

today?

I wouldnt touch a diesel... far too unreliable now. and thats without missfueling.
Diesel or Petrol - bintang
My annual mileage is 10,000 so no economic justification for diesel, but I would greatly appreciate having to refuel less often. I am not convinced by the pollution argument. There is less carbon monoxide produced but more carbon particulates. As the engines are heavier, car noses must be too. There have been adverse comments on this site regarding dual-mass flywheels fitted to some models but the 1.3, as used in small Fiats and the Yaris seems to attract a lot of praise.

But I have no direct experience. Over 57 years of driving I have owned 26 cars and must have driven at least 70 others, hired, borrowed or provided with employment, yet have never found myself behind the wheel of a diesel. Even the tracked Bren Gun carrier I learned on had a petrol engine.
Diesel or Petrol - bell boy
its got a DPF i believe so i really dont see the point if you only do 8k a year
Diesel or Petrol - DP
far too unreliable now. and thats without missfueling.


I disagree.

Our company fleet has a brace of Renault and Vauxhall turbodiesels, mostly with the 1.9 litre variant of both manufacturers common rail engines. These are now in their third generation / replacement cycle, and most of them have between 80,000 and 120,000 miles on the clock when they are returned at the end of a three or four year lease. The number of breakdowns or service hours lost to mechanical faults has never been lower at any point. the company renews them because they work well, are cost effective, and are popular with their drivers.

These drivers include field engineers and other personnel who are bound by SLAs with clients, and who can incur substantial penalties for the company if they arrive late due to a breakdown or fault. The diesel engines are simply not an issue and work as well at 120k as they do when new.

Next time you're on the road, look at how many cars carry dCi, TDCi, CDi, d etc badging, and then try and remember the last time you saw one dead by the side of the road.

Cars are becoming more reliable with every generation, diesels included. The modern diesel I have no doubt is more reliable than anything that has gone before. What is fair to say is that if a common rail does go wrong out of warranty, the bills can quickly become astronomical. I think it's also true to say that many mechanics don't understand how they work, further complicating repair processes and adding bills. They surely cannot be considered to be unreliable though, by any measure.

Misfuelling is a big concern, I agree.

Cheers
DP

Edited by DP on 05/07/2009 at 14:08

Diesel or Petrol - bell boy
Next time you're on the road, look at how many cars carry dCi, TDCi, CDi, d etc badging, and then try and remember the last time you saw one dead by the side of the road.
>>>>>>>>
>>>>>>>>>ask any mechanic what they are like and has he ever worked on any of them and why,he will site many things but i dont think he will say he enjoys working on the modern diesel no matter how its built
that would be a better barometer than looking for dead ones in the gutter :-)
Diesel or Petrol - the swiss tony
that would be a better barometer than looking for dead ones in the gutter :-)


The AA, RAC and all are pretty quick these days aren't they... 35mins last time I called them!
Diesel or Petrol - DP
Fair comment bb, but surely all modern cars are hateful to work on, and seemingly designed to make life as difficult for the non manufacturer diagnostic kit and special tool rigged tech as possible.



Diesel or Petrol - Chris M
But DP, you are looking at it from the high mileage user, not the 8k a year that the OP quoted.
Diesel or Petrol - DP
But DP you are looking at it from the high mileage user not the 8k
a year that the OP quoted.


Chris - yes I apologise my comments were not directly relevant to the OPs question, but I was merely disagreeing with the idea that modern diesels are inherently unreliable. They just aren't. No modern mass produced car is unreliable.
Diesel or Petrol - Avant
As a finance lecturer as well as a motoring enthusiast, I firmly believe that finance has to be an element of any major decision-making, but not the only element.

Personally I'm not a boy-racer but I like to get a move on: therefore I value good low-down torque in an engine above the ability to give the best at high revs. So a good diesel engine has its merits even for someone who does a moderate mileage, provided that the extra cost isn't prohibitive.

That said, there are more torquey petrol engines appearing now - from VAG for example - and although I have a diesel Octavia vRS I was sorely tempted by the petrol version, and it was only my current 20k annual mileage that swung it towards the diesel.

Diesel or Petrol - Toyota Red
hmm, I'm not sure it is fair to say that all cars are becoming more reliable all the time- Look at Toyota's 1.4 VVT-i that replaced the 1.3 4E-FE for example.

Cars with more gizmos are likely to go wrong more often. I'd agree that things generally get better as time goes by, no doubt about it. But it certainly does not hold in all cases.

Given the quite astonishing change in power output achievable from many diesel engines in the last decade, I would be scepticla about passing judgement about their longevity until the current generation are well over 5 years old. The extra performance will not come 'for free', and there are more than a few reports of problematic flywheels and swirl flaps (whatever they are!).

As to the original poster's question, despite rather enjoying the low-down torque of a modern diesel, and having driven many more miles in diesels than petrols, I simply find petrols to be a more pleasant experience. I guess part of that is due to the reduced noise levels, and lighter handling. I'm not sure a diesel would enjoy short trips much although neither does a petrol.

Edited by Toyota Red on 05/07/2009 at 16:27

Diesel or Petrol - Old Navy
I have owned diesels since 1989 and have never had a diesel related breakdown, I used to run my cars to about 100,000 miles. I drive diesels because I prefer the engine characteristics, and have never been accused of holding up the traffic, now retired I only drive about 15,000 miles a year but will continue to use diesel, probably changing my car on age rather than mileage.

Missfueling is self inflicted, and cannot be blamed on diesel cars, anyone, or anything. Accept responsability for your mistakes.

Edited by Old Navy on 05/07/2009 at 16:35

Diesel or Petrol - cuthbert
This is an interesting thread !!

I think people do not buy a diesel just for the fuel economy now but like myself find the driving experience and the torque that diesel gives you just makes a more relaxing drive .

With the amount of speed cameras on our roads now top end speed is irrelevant

Manufacturers are now tackling the problem of misfueling
Diesel or Petrol - David Horn
Can't fault mine, dunno why anyone would want to drive a petrol engine any more. (Noise / pollution issues aside).

My Passat delivers 50mpg if I thrash it, 60mpg if I don't, and it has so much torque that no hill is an issue, even at low revs. Used to have a Honda Accord, you had to rev the nuts off it to get anything like the same performance.

It's worth paying the premium for the more relaxed driving IMHO.
Diesel or Petrol - Snakey
I was all for diesel a few years back. Now still doing 20,000 miles a year I average 42mpg. With a decent petrol (say a bog standard 1.6 Ford Focus/Vauxhall Astra) that would probably be around 35mpg

My calculations showed it would cost me only £3-400 extra a year to run the petrol. But in my experience repairs on a diesel are so horrendously expensive (DPF,DMF,EGR valves and the dreaded fuel pump) that one failure can wipe out several years saving.

Now I'm keen to go back to petrol. I like the driving characteristics of a diesel (especially on the motorway) but petrol can be a lot easier to live with long term.

And wait until about Sept/Oct when diesel is around 10-15p a litre more expensive again!
Diesel or Petrol - gordonbennet
It's always a difficult decision and not made any easier trying to pre-guess the likely next move by Dick Turpin (aka the chancellor) and what he's likely to do next to VED or any other tax.

Going with that theme, it's probably better VED cost wise to go for a diesel today..that could change however with the next emission fashion fad.

I note many posters enjoy the extra torque Diesel brings, but we mustn't forget that we are usually comparing a turbocharged Diesel to a NA petrol of similar capacity and pronouncing the Diesel better.
If you compare turbo petrols with turbo Diesels then the easily available performance is probably in the petrols favour.
And those of us that ran NA Diesels remember oh so well the yawning performance usually available.

On running costs i had my eyes opened by our very own Humph when he ran a 2.2 Signum petrol and Mondeo Diesel side by side for some time, and found almost no difference in the fuel costings.
I much prefer to see real user results over makers claims.

The OP though is specifically asking about short trip running in the car...unless he's able to find a vehicle that doesn't have DPF or any other voodoo magic add ons to lower emissions a very modern diesel may not be the best choice at the moment IMO.
Diesel or Petrol - DP
Re driving characteristics, we have a 130 bhp diesel and a 180 bhp petrol. In the vast majority of driving situations, the diesel feels the quicker of the two, despite being quite significantly (>1 sec 0-60) slower on paper.

The petrol makes a far nicer noise, and is ultimately quicker if you let it rev, but it all feels a bit of a faff after the diesel which just lobs you up the road as soon as you squeeze the loud pedal. The petrol's hardly gutless, but you need to work it hard to get anything like the same result from it.

In a lightweight sports car that I want to drive the wheels off, it would be petrol all the way. In modern, heavy daily drivers, I'm a diesel convert. Despite the horrible noise.

gb - turbocharging a diesel doesn't have anything like the fuel economy penalty that turbocharging a petrol brings. The diesel engine could have been designed for turbocharging due to its unthrottled air intake.

Edited by DP on 05/07/2009 at 19:51

Diesel or Petrol - gordonbennet
gb - turbocharging a diesel doesn't have anything like the fuel economy penalty that turbocharging
a petrol brings.


Fair comment.

However we are seeing some new petrol turbo's being released, it'll be interesting to see how they go...as up to now petrol turbo's have been mainly designed for performance only.

Diesel or Petrol - daveyjp
If the Focus has a DPF avoid at all costs - it will be flagging problems after only a few thousand miles of pootling round town.
Diesel or Petrol - Sofa Spud
Aston martin celebrated coming 5th at LeMans this year, because they had the highest placed petrol car. The first 4 places were taken by diesel cars. Diesels have won LeMans for the last few years now.

The future of the internal combustion engine is in the developemnt of the diesel engine.
Diesel or Petrol - MikeTorque
My Focus 1.6 TDCi copes with everything thrown at it, short journeys, medium, long, slow speeds, stop/start etc. I've never had any problems with the DPF. It's a lot more economical and cleaner emissions than a 1.6 petrol.

The thing to consider is during winter time it takes longer for a diesel engine to warm up compared with a petrol engine which means the heater won't provide internal heating as quickly as a petrol engine. However, if your short journeys are stop & start type and engine stays warm to some degree between journeys then either diesel or petrol would be ok, but ensure you give the car a longer run (20+ miles is enough) once in a while to help blow out the engine and exhaust system. All cars/engines benefit from a longer run once in a while.
Diesel or Petrol - L'escargot
When it comes to acceleration, much (if not all) of the higher engine output torque of a diesel compared with a petrol is cancelled out by the higher gearing. I've yet to come up behind a 1.9 or 2 litre diesel which has been able to accelerate away from my 2 litre petrol.
Diesel or Petrol - daveyjp
"My Focus 1.6 TDCi copes with everything thrown at it, short journeys, medium, long, slow speeds, stop/start etc. I've never had any problems with the DPF. "

With such a mix of journeys you never should have a DPF problem - I've never had one either, but doing 15k+ a year of mixed driving I don't expect to.

8,000 mainly town miles may cause problems - I suggest the OP reads the sections in the handbook about DPFs before commiting to a DPF car.
Diesel or Petrol - davidh
When it comes to acceleration much (if not all) of the higher engine output torque
of a diesel compared with a petrol is cancelled out by the higher gearing.


I'm not sure thats true. Why do turbo diesels literally fling you up the road on a big gob of torque with the slightest sqeeze on the throttle then?

Why can overtakes be executed with huge thrust compared to winding up a petrol into a frenzy then grabbing another gear mid-manoeuvre?

I've
yet to come up behind a 1.9 or 2 litre diesel which has been able
to accelerate away from my 2 litre petrol.


I had the freak of chance to drive a manual BMW 325iSE and a 130 Golf GTTDi back to back over the same urban route within an hour of each other through having to borrow company cars to run an errand.

The Golf had 130 BHP, the 325i 192 BHP.

All I can tell you was that the Golf felt significantly faster and more relaxing to drive, the BMW felt limp and gutless. Only when I reached a dual carriageway and allowed the BMW its head, did it then feel significantly faster than the Golf.

How many times you plant your foot wide open on the throttle in daily driving I dont know - maybe when entering a motorway.

Bottom line:- Golf 1 BMW Nil. (I'm not pro Golf or VAG Td particularly just telling it like I found it)
Diesel or Petrol - L'escargot
>> When it comes to acceleration much (if not all) of the higher engine output
torque
>> of a diesel compared with a petrol is cancelled out by the higher gearing.
I'm not sure thats true.


To prove that it's true, you only have to calculate the torque at the road wheels (which, for similar rolling radius tyres, is the relevant parameter) by multiplying the engine output torque by the ratio of the rotational speed of the wheels to the rotational speed of the engine, to take into account the higher gearing of a diesel. It's just a matter of simple arithmetic.

Edited by L'escargot on 07/07/2009 at 07:44

Diesel or Petrol - Andy P
If you want an example of diesel reliability, a friend of mine has an Alfa Romeo 2.4FJTD Sportwagon that has been chipped to 200bhp. Over the 115k miles he's had it, the engine hasn't caused any problems.
Diesel or Petrol - davidh
I know the maths, but I also know what the seat of my pants tells me.

Driven "normally" a turbo diesel "feels" quicker and seems able to keep its speed more when encountering a hill.

Probably due to how the engine can keep piling on the torque.

Another example, my CDTi 150 Astra "feels" quicker in any gear you want to name than my old 200bhp turbo Rover 620ti. It'll throw you up a hill - If you live somewhere flat, you may not fully appreciate this phenomenon. A wheel spin competition or an outright dual carriageway drag and the Rover would win it.
Diesel or Petrol - DP
I completely agree, David.

SWMBO's Golf GT TDI (130 bhp) feels far perkier than my 180 bhp Volvo S60 2.0T petrol until you get it on open roads and start using the revs. Then you feel the petrol's ability to sustain the acceleration into high revs where the diesel runs out of puff. The Volvo's acceleration swells beautifully around 3-4k just where the Golf is needing another gear. Translate this into a side by side race, and you can see that the Volvo would pull away convincingly at this point. However, the Golf would have pulled out a lead before this due to the wallop it delivers at low to medium revs. I have never raced the two cars, and I know the Volvo is the faster from a standing start, but you need to work the petrol engine so hard to deliver what the diesel does with a simple flex of the right ankle.

At town speeds, or during stop / start driving where you're spending a lot of time in the bottom half of the rev counter, the diesel simply produces more torque and more power. That is the hard fact of it. I can take the Golf for a blast around the lanes, and simply leave it in 4th. That gives me back-in-the seat acceleration from 35 mph to well over the legal limit. If I need to squirt into a gap, or my favourite activity in the Golf - join a motorway, the on-tap grunt is verging on breathtaking for a small, cheap family hack.

In something like a Caterham or an Elise, which I'm likely to thrash everywhere, or in a big car which I'm not paying the bills on, give me a petrol engine. Otherwise I'm a diesel convert.
Diesel or Petrol - L'escargot
I know the maths but I also know what the seat of my pants tells
me.


I'm talking about the truth of the comparison, as indicated by acceleration times. Give me scientific facts, not seat of the pants impressions.
Diesel or Petrol - Brian Tryzers
It's your assertion, M. Escargot; how about you giving us the maths to back it up?
Diesel or Petrol - perro
If I was doing the miles I'd consider a diesel, but I don't so I won't + I'm a dyed in the wool petrol head and don't really like diesels ... I've had a couple - AX 1.4 and a Disco both no prob til I tried to change the fuel filter and got air in the system - the little Citroen was actually a blinder and I drove it to Tenerife & back (via Cadiz) and it never missed a beat, but obviously it was fairly low tech compared to today's oil burners which have almost as much electronics as a petrol job.
Diesel or Petrol - L'escargot
........... how about you giving us the maths to back it
up?


The only authoratitive documented evidence that I have to hand of a comparison of similar size engines in a given car with a manual gearbox is from an April 2008 Ford Focus brochure. This gives a 0-62 mph time of 9.2 seconds for a 2 litre petrol producing 145 PS maximum power and 185 Nm maximum torque, and a 0-62 mph time of 9.3 seconds for a 2 litre TDCi diesel producing 136 PS maximum power and 320 Nm maximum torque. Note that although the diesel has a maximum engine output torque of 320 Nm compared to a mere 185 Nm for the petrol the difference doesn't result in better acceleration for the diesel. As I said before, it's torque at the driving wheels that is the relevant parameter and this depends on the overall gearing. The torque at the driving wheels is inversely proportional to the overall gearing ~ quoted in, say, mph per 1000 RPM engine speed ~ and the higher gearing of the diesel is the reason it loses out to the petrol.

At one time there was a magazine which gave acceleration times for conditions other than 0-62 mph but I can't remember what it was or whether it's still available.
Diesel or Petrol - David Horn
0-60 times for my brother's diesel A5 beat the petrol version by a considerable margin.
Diesel or Petrol - nortones2
Only motoring journalists do 0-60! In the real world, its rolling acceleration that matters. Autocar and others in their tests list a number of other characteristics, like in-gear acceleration, which are more realistic. They don't depend on brutal techniques that no sane owner would tolerate.
Diesel or Petrol - lordwoody
Is the A5 diesel that much better? Assuming you're comparing like with like, the 2.0 TDi does 7.9/8 sec, 2.0 petrol around 7.8 sec.
Moving up the engine scale, 3,0 diesel, around the 5.7/5.9 secs, 3.2 petrol, 5.9/6.4 secs.
I don't see any A5 figures favouring the diesel "by a considerable margin"

Edited by lordwoody on 08/07/2009 at 11:20

Diesel or Petrol - ifithelps
From the Ford Focus e-brochure:

2.0 petrol: 31mph to 62mph in gear acceleration: 11.9 secs
2.0 Tdci: 31mph to 62mph in gear acceleration: 7.8 secs.

The diesel is four seconds quicker, which in this context is a lot.

0-62mph is about the same, 9.3secs for the diesel, and 9.2secs for the petrol.

Given the importance of in gear, or rolling, acceleration, the diesel is the one to have.
Diesel or Petrol - LikedDrivingOnce
That's just weird!
2.0 Petrol can do 0-62 in 9.2 secs, but if it is already travelling at 31 mph, it can only do 31-62 in 11.9 secs.
There must be a rational explanation for this.
Diesel or Petrol - TimOrridge
That's just weird!
2.0 Petrol can do 0-62 in 9.2 secs but if it is already travelling at
31 mph it can only do 31-62 in 11.9 secs.
There must be a rational explanation for this.


Yes 30-60 will be in a given gear, maybe 3rd? Whereas 0-60 will be "thru" the gears.

Edited by TimOrridge on 08/07/2009 at 13:41

Diesel or Petrol - LikedDrivingOnce
Your explanation sounds logical to me.
In which case, I'd like to see the 31-62 times "through the gears" to mirror real-world driving, then.
Diesel or Petrol - ifithelps
...That's just weird!...

Pretty sure I lifted the figures correctly :)

Something to do with gears used or gearing?

Either way, I think it illustrates why so many people like modern diesels.

As DP said further up the thread, just flex your right ankle and the overtaking grunt is there.

Diesel or Petrol - L'escargot
As DP said further up the thread just flex your right ankle and the overtaking
grunt is there.


The "overtaking grunt" is there in my 2 litre petrol as well. And I don't have to suffer all the diesel noise and smell.
Diesel or Petrol - apm
Our S60 D5 feels faster than my previous Leon Cupra petrol, despite similar power and the Leon being lighter (185 bhp v 180 bhp). It's the great fat globs of torque available from the first spin of the turbo! My motorbike, as a total contrast is very peaky, producing about 100bhp but not alot until about 6k rpm. The bike is ultimately an awful lot faster (revs to 12500), but the grin-inducing torque from the D5 always brings on a grin, and makes it very useable in most kinds of traffic.

Re misfuelling, we've not done this, but as the consequences are potentially so bad for a moment's inattention, we bought a fuel angel (google it for more info) for about £30 which means the unleaded nozzle won't fit in the filler any more. Sorted.

If it were me, I'd try examples of both engines types and see which I liked most.

Cheers,

Alex.
Diesel or Petrol - L'escargot
2.0 petrol: 31mph to 62mph in gear acceleration: 11.9 secs
2.0 Tdci: 31mph to 62mph in gear acceleration: 7.8 secs.
The diesel is four seconds quicker which in this context is a lot.


That's keeping in one gear ~ probably 4th ~ and who does that? I certainly don't.
Diesel or Petrol - davidh
L'escargot,

Just book yourself a test drive in a modern turbo diesel and then come, back to us.
Diesel or Petrol - L'escargot
Just book yourself a test drive in a modern turbo diesel and then come back
to us.


Wash your mouth out. I've got too much respect for my Gucci shoes at filling up time!
Diesel or Petrol - drbe
Wash your mouth out. I've got too much respect for my Gucci shoes at filling
up time!

>>

But you are prepared to have lubricating oil in your mouth!
Diesel or Petrol - L'escargot
But you are prepared to have lubricating oil in your mouth!


I didn't explain the precise method I used. I attached second (1 metre long) piece of clear PVC tube onto the first piece which had been inserted into the dipstiick tube and which would carry the oil. The second piece was slightly larger in diameter to the first and the two pieces were connected by merely inserting the first piece into the second piece. The fit was good enough to form an airtight seal between the two pieces. I sucked onto the open end of the second piece until the oil reached the end of the first piece. I then separated the two pieces of tube and immeciately lowered the then open end of the first piece into a container to catch the oil which would be siphoned out. The oil didn't come closer than a metre of my mouth so their was no risk of it getting into my mouth. I'm not as green as I'm cabbage looking!

Edited by L'escargot on 09/07/2009 at 08:23

Diesel or Petrol - ifithelps
...That's keeping in one gear ~ probably 4th ~ and who does that? I certainly don't...

Just checked the ebrochure.

It says the figures are in fourth gear - seems they drive both the petrol and diesel the same way for the test.

As regards accelerating hard from 31mph to 62mph in one gear - why not?

I certainly would if it meant for a safer overtake.

Diesel or Petrol - brettmick
50-70 or 30-60 is usually in top gear, as the revs are so low the diesel will always win this due to torque. The old 1980s Saab 900 was faster in gear than some supercars and I understand was a big marketing thing.

I had a 150 Diesel Saab 93 which we recently replaced with a 1.8 T petrol A3. This was mainly because I am not doing the mileage now and the Audi 170 Diesel was £1,500 more.

The 1.8T Audi is quicker 0-60 and is also a 6 speed gearbox. In the Saab I could leave it in 6th at 75 and get a decent burst, in the Audi it is best to drop to 5th. The Audi is far quieter and the long run of power from the FSI engine from 30 to 80+ in 3rd is very satisfying - but peak torque is very low in the rev range for a petrol.

Not sure it is fair to compare a normally aspirated petrol with a turbo diesel.

What do I prefer? Not sure it is fair to compare like for like. If I were to buy an A4 avant I would go 170 Diesel for economy and torque when lugging the weight, any convertible for me must must be petrol. As with anything each persons needs are different.

Diesel or Petrol - MikeTorque
Turbo diesels are relaxing to drive, stick um in any gear and let the torque handle the acceleration.

A turbo petrol, on the other hand, offers the best of both worlds, similar revs to a typical petrol engine and similar torque to a turbo diesel engine.
 

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