Can anyone help me,
I am after buying a newer car, and I have spent the whole weekend looking round dealers.
I want some advice on weather I should buy a petrol or a diesel car. I want to spend about £5000. I have looked at Mondeos, Passats, Peugots and Audi's as this is the size car we want.
Is it false economy to buy a diesel car if you dont do motorway miles or high milage, or is a petrol as economical.
I start a new job soon driving round sheffield to different places, I will be obviously doing more miles than at present, so can someone help shed some light on the situation..

replies to www.nicholawest@aol.com

Many thanks

diesel is more efficient whatever sort of driving you are doing, but you need to be doing reasonable miles I would think to offset the higher initial purchase price.

Diesel anyday, cheaper to run regardless of local / motorway usage and if its a 'Y' plate onwards (2001) you'll most likely pay less car tax too

Diesel, it may be a bit more at the pump but it's better. It can be a bit slower off the mark though.

Don't buy a brand new car though! Get a second hand one any time, otherwise you really are throwing money away.

Having recently helped my friend with almost the same task it seems that diesel cars of this price about 2-3 years old are £1000 more expensive to buy, than their petrol equivalents. And the fuel savings are made on slow diesel cars, the fast ones have much worse fuel economy and it makes no sense to have a diesel engined car with petrol engine performance.

I understand that if you are doing lots of motorway miles you would be mad not to get a diesel, because it won't take you long to pay back the extra purchase costs and more expensive servicing of a diesel.
However, if you are making lots of small journeys you would be better off with a petrol because they take less fuel to start and start easier, due to lower compression.

Other things to think about are how much quieter and more pleasent petrol cars are and the effects of turbo lag on a turbo diesel car can you cope with it, some of them can be quite frightening to some people.

Originally posted by muddycoffee
Having recently helped my friend with almost the same task it seems that diesel cars of this price about 2-3 years old are £1000 more expensive to buy, than their petrol equivalents. And the fuel savings are made on slow diesel cars, the fast ones have much worse fuel economy and it makes no sense to have a diesel engined car with petrol engine performance.

I understand that if you are doing lots of motorway miles you would be mad not to get a diesel, because it won't take you long to pay back the extra purchase costs and more expensive servicing of a diesel.
However, if you are making lots of small journeys you would be better off with a petrol because they take less fuel to start and start easier, due to lower compression.

Other things to think about are how much quieter and more pleasent petrol cars are and the effects of turbo lag on a turbo diesel car can you cope with it, some of them can be quite frightening to some people.

of course Taxis and buses rarely make motorway journeys, and they are still diesel, I think it's more about the number of miles, rather than the speed they are done at.
I'm intrigued now about performance diesels and their efficiency, i'll have to go and look some up on parkers.
And the modern HDI diesels (aka common rail or direct rail injection) are much quieter than the previous generation of diesels, although still noisier than petrol.

Research done.

Whilst faster diesel powered cars are less efficient than slow ones, they still have a considerable edge over petrol cars of the same performance.
The BMW 530d
530d SE (231bhp) 4d 05 2993 / 6 227 155 6.6 42

6.6 s 0 -60 and returning 42 mpg combined.

the fractionally faster 530i
530i Sport 4d 04 2979 / 6 231 155 6.7 29

6.7s but only 29 mpg.

Or fractionally slower 530i auto
530i SE 4d Auto 03 2979 / 6 231 152 6.9 28

6.9 and 28 mpg.

Basically, not even the smallest petrol engined 5 series is anywhere close to the 42 mpg and 6.6s is pretty damn fast for a big fat car like a 5 series.
If performance is less important you can eak{sp} another 5 mpg out of it by having the slower 520d
520d 4d 05 1995 / 4 160 139 8.3 47

8.3s 0 - 60, but nearly 50 mpg.

I always run a diesel car because of the high mileage I do (about 45000 a year), but recently looked into the effect of a cheaper initial purchase price of a petrol car and cheaper fuel to see whether it would be any cheaper to run.

It worked out that over the first 12 months, petrol would be cheaper but after that, the extra mpg negated this and in the long run it came back again to diesel being cheaper, both in terms of fuel consumption and things like servicing (30,000 intervals on mine).

Mine isn't a typical case I know but even with learners driving for the majority of the time, I get between 45 and 50 mpg (1.3 Corsa CDTI).

Originally posted by Cyclone
of course Taxis and buses rarely make motorway journeys, and they are still diesel, I think it's more about the number of miles, rather than the speed they are done at.

Yes but the crucial difference here is that they don't swich their engines off, they keep them running all day. If you do this then a Diesel engine is very efficient overall.

Cyclone, I cannot make head nor tale of your list of numbers.

Apart from your summary of course.

If you compare a similar diesel and petrol engine of the same power, and drive them exactly the same high speed around a race track, I doubt that there would be much difference between their mpg. The only way to increase the performance of an engine is to get it to burn more fuel, burn the exisiting amounts of fuel more efficiently or reducing the load.

If diesels were all that good they would use them for rally cars.

I am sure that if you drive the diesel car quietly and frugally at low speeds and the petrol similarly then the diesel would be much more efficient in it's economy.

I got them from www.parkers.co.uk if you want to check yourself.

Basically it was a comparison of the petrol and diesel versions of one model (the BMW 5 series) and choosing examples with the same 0-60 time (as a representation of performance).

The relevant facts were that the petrol engine gets <30 mpg, whereas the diesel gets >40 mpg for a relatively high performance (6.6 seconds).

If you went for slower the diesel increased to nearly 50mph, the petrol to just over 30 mpg.
The savings are greater for lower performance cars, but definitely still there for higher performance examples as well.

So you're assertion that

And the fuel savings are made on slow diesel cars, the fast ones have much worse fuel economy and it makes no sense to have a diesel engined car with petrol engine performance.

is wrong. When comparing like for like.

You may well be right though about short journeys, i've no idea where to check that information, but it sounds reasonable.

remember - NEVER buy new!! buy one year old and you can save yourself a packet!!!

Hi Cyclone,

well it's interesting that you had to choose a car like a BMW 5 series, when most people would be choosing diesel cars which are in a much smaller class, and cheaper class.

My boss used to have a BMW 5 series, it was a 2L petrol and it had a straight 6 cylinder engine. He bought it when it was a few months old, and to be honest it was like driving a 1.3litre cortina around town. It was much better on the motorway but the car was so overweight and underpowered that I feel it is a bit unfair to use it as an example for such a comparison.

In my opinion, Saxon's testimony is the most useful to the average person reading this because it shows the kind of milage a smaller or family car would have to do, every year to make savings with diesel fuel.
When you bear in mind that average milage is considered to be around 10-12,000 a year, the answer for most people would be buy a petrol engine.

Along similar lines, the balance has shifted so far, that now most minicabs are petrol because there is no saving for them, with a diesel engine. Only 5 years ago almost every minicab was diesel because it was much cheaper than petrol, and they made more money.

Ermm, yeah, but you were talking about 'faster' diesels. I don't think you can get a 'fast' diesel corsa, I was pretty sure that you could get a fast 5 series.
What types of 'faster' diesels were you talking about if it wasn't performance saloons?

I can choose any car you like, and if there's a fast diesel version available it will be more efficient than the equivalent petrol. Tell you what, you see if you can find one that isn't.

Saxon's testimony is very interesting, but i'm not sure it supports what you just said.
If it takes Saxon one year (ie 45k) then it might take someone else 4 years (12k/year), but a lot of people keep a car for longer than that, and I'll hazard a guess that Saxon buys new, so the gap would be shorter if you were buying 1 year old.
If it's 3.5 yrs at average miles and you plan to keep the car for that long, then it's breaking even, longer than that and the diesel should be cheaper.

I've been doing 20 - 30 k/year, so a diesel would have been the sensible choice, but now i'm taking the train so that's dropped to about 6k, sticking with the petrol for the time being.

Originally posted by scottf
remember - NEVER buy new!! buy one year old and you can save yourself a packet!!! But someone else has been farting in your seat for 1 year.

Originally posted by scottf
remember - NEVER buy new!! buy one year old and you can save yourself a packet!!!

Actually, 'if you buy new then haggle more' would be a better piece of advice. I bought new, but with a £3,000 discount, which made it considerably cheaper than the 12-18month old models they had parked outside the dealership. NEVER pay full price :)

Originally posted by muddycoffee
Only 5 years ago almost every minicab was diesel because it was much cheaper than petrol, and they made more money.

Thats due to the government cashing in on the popularity of diesel vehicles

There is too many factors to think about here..

Mileage
Age of car when bought
Time you are likely to keep the car

It doesn't matter what type of journeys you do, in like for like cars the diesel will be more economical than the petrol.
Lots of people have stated the higher initial price of a diesel, but if your are planning on replacing after say 2 years then your resell value will be higher. eg. You pay an extra £1000 for the diesel. 2 years later you will still get £750 extra if you sell. That means that the saving on economy only has to be £250 to be making a profit.

On the other end of the scale, I go for the older car. My current car is a 1700 TDiesel Astra Estate. P 1996. Cost me £1400 just over 3 years ago. I've added about 60k on the clock (now showing 150k, most petrol engines would have died a long time ago). Apart from when I tried to kill it using the M18s central barrier :( its cost me about £200 to keep running (most of that on a alternator). The last MOT cost £70 (including repairs and MOT) the first 2 cost just the MOT fee.

Get an old diesel n run it on vegetable oil, I'm sure the local chiipy owner will be glad to give you their used stuff :thumbsup:

my petrol engine is still going strong at 145k, doesn't use water or oil, not had any problems (apart from ones I cause).

Our relative has a diesel-based Volvo V50, and she goes zooming off around the country in it. It's very quick - maybe 3.2L - not sure.

It has 6 gears, and it hates being 'laboured'. Although when Mr Relative drives it, it doesn't get a choice. Apparently it went back over christmas, as it wouldn't rev over 5,000rpm properly.

:)

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