# Pros and Cons buying a diesel



## Berbatov (20 Nov 2007)

Thinking about buying a diesel car ...just wondering anyone have any advice on pro's and cons of buying a diesel car...like i'm told fuel consumption should be much better?...is this correct?..i see in most garages around now diesel is the same or slightly more expensive than unleaded petrol..looking for advice .


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## joeysully (20 Nov 2007)

PROS
I went From a 1.9 non tubo deisel to 1.6 petrol and wow did i see the difference in fuel costs. at that time deisel was ~10c cheaper but even adding the same ammount of fuel it just did not go as far. probably 40% less mileage. i think deisel price  will come down again.
Engine Noise - padestrians dont walk out in front of you 

Cons
service interval increases - this might not be so true for newer deisels
ROAD TAX ~ 350 for 1.6. ~ 530 for 1.9 (.905 up)
DEAD - staright deisel ie non turbo are a bore to drive. getting a TDI is best and probably more fuel efficient.


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## Frank (20 Nov 2007)

Good MPG 
easier to drive because of extra torque.
tend to last longer because the fuel is closer to oil therfore not corosive on the engine parts like petrol.

Modern diesels are as good as and better than a equivelant petrol. Service intervals are the same as petrol now

Downside
Generally dearer to buy initially.
Well worth it though.


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## RS2K (20 Nov 2007)

Fuel economy is a lot better. Better torque or pull in each gear. Less downshifting for overtaking. Better residual values. 

More expensive to buy, some need more regular servicing, may be a bit noisier particularly on start up. Engines tend to be bigger capacity so tax and insurance may be pricier.


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## Simeon (21 Nov 2007)

Noisier to start (but not that much if looked after), far better fuil wise, Eu 511 for a 1.9 and the price should come down again. In Merrion it was 2c a litre dearer than unleaded today ........ but that happened during the last 'crisis' also before dropping well below unleaded after a while.


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## Giggsey (21 Nov 2007)

The main con of buying a diesel is the cost. 
ROAD TAX ~ 350 for 1.6. ~ 530 for 1.9 
Plus a diesel car initial cost is a lot more than petrol equivalent.

You are saving on mpg, but I saw a table before which showed in order
to make back the extra cost of diesel you have to be doing an awful lot
of milage each year.
Conclusion was diesel only makes sense for taxi driver/sales rep....

I did a search on web for table and only found a UK example below. Its says
3 years to re-coup cost (but I think its more for Ireland with Tax, and bigger diff in initial price...)



***************************************
Here's the comparison between the 335i and 335d as Coupes in SE spec.

BMW 335i SE
Purchase price: £33,795
MPG: 29.7
CO2: 228

BMW 335d SE
Purchase price: £35,870
MPG: 37.7
CO2: 200

I'm using petrol @ 92.9p/litre and diesel @ 94.9p/litre.

You must travel 68000 miles over three years before the diesel evens out against the petrol. This is including tax liability for two years (1st year included in purchase price) but not servicing costs as it's proving extremely difficult to get that info from car manufacturers.

The fuel costs over the 68000 miles are:
335i: £9,669.36
335d: £7,781.50


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## aircobra19 (21 Nov 2007)

joeysully said:


> PROS
> I went From a 1.9 non tubo deisel to 1.6 petrol and wow did i see the difference in fuel costs. at that time deisel was ~10c cheaper but even adding the same ammount of fuel it just did not go as far. probably 40% less mileage. i think deisel price  will come down again.
> Engine Noise - padestrians dont walk out in front of you
> 
> ...



You can buy small turbo diesels like 1.3/1.4 and that negates the tax and insurance issues.

Main difference is the noise, and the extra you pay to buy diesel engine. You have to work out, if this premium is covered by the savings you make in fuel costs.


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## Nairb (21 Nov 2007)

Giggsey said:


> Here's the comparison between the 335i and 335d as Coupes in SE spec.
> 
> BMW 335i SE
> Purchase price: £33,795
> ...


 

If you factor in the increased resale value of the diesel it may make more sense.
I'm also thinking of getting a diesel, am doing about 25k pa so based on those figures it would make sense.


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## aircobra19 (21 Nov 2007)

Even if you pay a more for the diesel, it might be worth paying for the extra range, less time at the pumps, and the extra torque which makes for easier driving. I know some people who use diesels for work, that have a tank at home. Doesn't save much money buying in bulk but it much easier to top up every evening at home, than having to go to garage, especially if there isn't a resonably priced one nearby.


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## Carpenter (21 Nov 2007)

I'm getting a diesel car in the new year, never having owned a diesel before.  Primary considerations were pulling power (or torque) and fuel economy.  I spoke to a couuple of friends who drove diesels before taking a couple of test drives in the the car I wanted to buy.  Heavier cars really suffer in fuel economy when an underpowered petrol engine is pushed above mid range.  I don't really do the extra mileage to warrant the €2000 extra I'm going to pay for the diesel engine (as against the 1.6 petrol variant on offer) but I decided to go with this anyway as I'd be happier that the diesel engine will not have to be pushed too hard in the course of the everyday driving I do.  There's nothing more frustrating than driving an underpowered car, especially when it's loaded up with a full complement of passengers and a boot full of gear as well.
I could probably expect to get a €1000 of this extra cost back when I come to sell on the car anyway, plus it should prove easier to sell.  The range of engines on offer with cars in this country is largely dictated by the tax regime (VRT and motor tax) with the result that a lot of bigger cars are offered with an entry level 1.6 petrol engine, which is underpowered for the job and quite clearly a diesel engine would be the better choice.


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## aircobra19 (21 Nov 2007)

A diesel will have better economy even in heavy traffic too.


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## gocall01 (21 Nov 2007)

The more miles you do per year the more sense it makes to go diesel.
I do about 20K miles and my wife about 15K miles a year.
We have both got diesels and will not be changing to petrol anytime soon.


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## Ceist Beag (21 Nov 2007)

It doesn't just boil down to money either - I have a 1.9 TDI and find it absolutely brilliant to drive - comfort is a factor to me that cannot be measured in monetary terms. So even if you factor in the cost difference if you drive long journeys you might appreciate the extra comfort and easy driving from a turbo diesel.


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## Berbatov (21 Nov 2007)

Can anyone tell me the difference between a common rail diesel injection system and turbo diesel?..is one better than the other??..thank to all for replies btw ...Looks like diesel is the way to go alright esp as im doing 20k miles per year...just seems to me with current petrol car i'm driving i seem to be  at the pumps more often than i'd care to be!!!


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## Carpenter (21 Nov 2007)

I'm no petrol head (or diesel head either!) but my basic understanding is this:

Turbo engines pump more fuel/ air mixture into combustion chambers and achieve more power from a given engine size than a non- turbo diesel.  The turbo "fan/ compressor" is driven off the vehicles exhaust gases.  I thought most diesel engines on offer now were turbocharged?


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## RS2K (21 Nov 2007)

All modern diesels are turbocharged. Common rail is a more modern method of increasingly accurate fuel injection with minute computer controlled adjustments. They are quieter, more powerful, and more economical too. 

If you are buying now a 2nd generation common rail engine should be your target.


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## sse (21 Nov 2007)

hi all

you may want to check out www.honestjohn.co.uk which is a fantastic site for the pros and cons of each make and model (no connection, btw)

other factors to consider:
- you'll probably find that the number of miles you have to do to offset the purchase price is surprisingly high
- in the UK there is now a glut of 2nd hand diesel cars so don't necessarily expect the tradein price differential to hold up
- modern diesel engines are, in many cases, now more complicated than their petrol equivalents - with turbochargers, EGR valves, common-rail injection
- service intervals have been pushed out to 18/19k miles to suit fleet contract hire rates, remember diesel combustion byproducts pollute the oil
- misfuelling a diesel car with petrol is annoying at best - if the engine is not started the tank needs to be drained and flushed - but catastrophic if a modern CR engine is run for any distance, so beware if buying used (the fuel acts as a lubricant)

SSE


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## Berbatov (22 Nov 2007)

i'm looking at a diesel car thats 4k more than its petrol equivalent...my question is are diesel cars that more expensive than their petrol equivalent???...looking at the advice gone before it could take many miles and years to break even when comparing fuel efficiency and cost of diesel car....4k diff could take 3/4/5 years to claw back.


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## aircobra19 (22 Nov 2007)

Thats why you need to do a lot of miles to justify the extra cost.


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## ang1170 (24 Nov 2007)

aircobra19 said:


> Thats why you need to do a lot of miles to justify the extra cost.


 
You should talk to someone who actually owns a diesel and get some "real world" experience.

Looking at manufacturer's mpg figures, it's true: you have to do a pretty high mileage to recover the initial higher cost.

However, my experience in actually having one is that there is a huge difference in fuel consumption between diesel and petrol: up to twice as far for the same €40 of fuel. If you ask anyone with a diesel car, they tend to have a similar experience.

In other words, don't rely on official figures when trying to calculate likely savings: try and get some actual figures.


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## aircobra19 (24 Nov 2007)

How on earth can you get so called "accurate figures"?  Ignoring the usual misleading BS you get on internet forums, fuel consumption will vary signifcantly depending on the type of journey, and the driving style of the driver. 

The official figure are a baseline guide you can compare different cars. They are achieved by driving in a very artificial way. Usually to get the max fuel economy out of a car, under those specific conditions. You can't expect to replicate them, if you drive in completely different conditions. Which may be more or less favorable than the official tests.


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## ang1170 (24 Nov 2007)

aircobra19 said:


> How on earth can you get so called "accurate figures"? Ignoring the usual misleading BS you get on internet forums, fuel consumption will vary signifcantly depending on the type of journey, and the driving style of the driver.
> 
> The official figure are a baseline guide you can compare different cars. They are achieved by driving in a very artificial way. Usually to get the max fuel economy out of a car, under those specific conditions. You can't expect to replicate them, if you drive in completely different conditions. Which may be more or less favorable than the official tests.


 
That's exactly my point: the official figures, although in theory an objective baseline, are in my experience pretty useless even for that.

The only meaningful figure is how much you use yourself. It's easy enough to measure how many litres of fuel you use to go so far. On the basis that my own driving or types of journey didn't change radically, I found that by going to diesel I was using maybe 40% less fuel (I can't recall the exact figure), for a similar sized car. From talking to others who've done the same, this does not seem to be unusual.


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## aircobra19 (24 Nov 2007)

If the official figures for car A were 20% better than for car Car B. Your saying that baseline is not useful and/or is not accurate. Perhaps its not accurate, but I would say its useful. 

How can you estimate how much diesel you'll use in a disimilar car. Considering it you'll drive it differently from your own. For example if you have a peaky 16v petrol you are going to rev it a lot more than you will a 2.0 TDi and cruise at a different speed depending how its geared etc. You just drive it very differently. Thats what I reckon anywayz.


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## UpTheBanner (25 Nov 2007)

fuels cost difference between diesel and petrol based on 18k miles per year and obtaining 45MPG and 35MPG for diesel and petrol respectively

Price €1.06 Diesel €1.14 Petrol 
MPG 45 Diesel 35 Petrol 
Annual Miles 18k
Total Fuel Price €1,927 Diesel €2,665 Petrol 

Saving €738


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## Fatphrog (25 Nov 2007)

I don't know where you buy your fuel (clare) but petrol seems to be about 2c a litre cheaper than diesel in the northeast.

45 mph = 9.9 miles/L     18k = 1818L diesel @ E1.2/L = E2181

35 mpg = 7.7 miles/L     18k = 2337L petrol @ E1.18/L = E2757

Difference = E576


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## ang1170 (25 Nov 2007)

aircobra19 said:


> If the official figures for car A were 20% better than for car Car B. Your saying that baseline is not useful and/or is not accurate. Perhaps its not accurate, but I would say its useful.
> 
> How can you estimate how much diesel you'll use in a disimilar car. Considering it you'll drive it differently from your own. For example if you have a peaky 16v petrol you are going to rev it a lot more than you will a 2.0 TDi and cruise at a different speed depending how its geared etc. You just drive it very differently. Thats what I reckon anywayz.


 
I'd say the official figures are not entirely useless, but they do tend to under estimate the benefits of moving to diesel.

I still say the only comparison that makes sense is the one I outlined: so what if there's some subtle difference in driving style between the two cars? I'm only interested in how much I pay at the pumps, not some notional objective figure, which will never be able to take personal driving style into consideration.


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## aircobra19 (25 Nov 2007)

ang1170 said:


> ...so what if there's some subtle difference in driving style between the two cars? I'm only interested in how much I pay at the pumps, not some notional objective figure, which will never be able to take personal driving style into consideration.



Driving style can make a big difference. You shouldn't drive a petrol same way as a diesel its inefficient. Subtle I don't think so...

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[broken link removed]




All I'm saying is the official figures are under test conditions. So theres some consistency in them. They are a useful baseline for comparision. 

But if a persons own driving isn't close to those test conditions, they might never do urban journeys at low speed for example, then of course they'll better the official figures. 

You said originally to ask someone who drives a diesel car. Thats like asking how long is a piece of string theres so many variables that could be a factor in someones fuel economy. He might be doing a 400 mile round journey twice a week. You might be parked on the M50 everyday.


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## smcgiff (25 Nov 2007)

Going on today's Sindo's VRT changes expected in the next budget, you'd want your head tested to buy a  petrol car now.


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## aircobra19 (25 Nov 2007)

smcgiff said:


> Going on today's Sindo's VRT changes expected in the next budget, you'd want your head tested to buy a  petrol car now.



Bit of a lottery to know for sure what they'll do. Based on the current govt track record.


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## smcgiff (25 Nov 2007)

aircobra19 said:


> Bit of a lottery to know for sure what they'll do. Based on the current govt track record.


 
You mean back tracking on motoring policy? Surely not!


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## ang1170 (26 Nov 2007)

aircobra19 said:


> You said originally to ask someone who drives a diesel car. Thats like asking how long is a piece of string theres so many variables that could be a factor in someones fuel economy. He might be doing a 400 mile round journey twice a week. You might be parked on the M50 everyday.


 
I still don't think you're getting what I said.

As you say, little point in asking someone what mileage they get in their car in the hope you'll get the same, as there are too many variables involved.

However, if you ask them how much their mpg increased from their previous (petrol) car, you should get a pretty good estimate of the potential savings.

My point (again!) is that when you speak to owners, the savings they quote are typically more than you'd expect from looking at the official and supposadly objective figures. 

Not very scientific I know, but as I also said, I think real world figures are the only one's that matter in the end: how much do I save in my choice of car.


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## aircobra19 (26 Nov 2007)

What you saying is if someone hammers their 1L Ibiza at 75mph home every evening getting 25mpg, then switches to 2.0 TDI and gets 55mpg. 

Then someone who does the same journey in say a 1.6 Civic at 60mph getting  45mpg or better should get about 90~100mpg if they switch to diesel.


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## ang1170 (27 Nov 2007)

I think your figures are a bit unrealistic, there.

40% or better improvement would be a better figure to use, rather than over 100%. One other poster apart from myself has used this figure, which is somewhat better than the comparison based on official figures quoted by another showed.

If memory serves, it was actually better than this over the long term, but it's not a bad figure to start with.


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## aircobra19 (28 Nov 2007)

Thats because   to demonstrate driving style. ​ 
So the guy getting 25 now gets 35
The guy getting 45 gets 63


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## ang1170 (28 Nov 2007)

Exactly: so if I happen to be getting (say) 30 mpg in my current petrol car, it's a good estimate that I'd be likely to get 42 mpg if I moved to a diesel (assuming a roughly equivalent car).

What the official figures say for either car is pretty much irrelevant, as they don't take into account individual driving style or journey type, and as I've said (many times at this stage) they seem to consistently underestimate the benefits of moving to diesel.


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## aircobra19 (28 Nov 2007)

I give up.


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