I am going to post two threads for advice on diesel cars. Both inter related but dont wish to confuse the two.
Firstly, I am considering changing to a diesel but a friend who was in the motor business for over 40 years has made me think again due to the mileage and the pattern of my driving.
I currently drive a Merc. 320 Estate petrol. Due to retire soon and need a car cheaper to run as I will be paying the bills - hence the diesel.
I will cover 6,000 to 7,000 miles a year, about 60/70% of the mileage will be on short runs of a few miles and my mate reckons that I will not get the economy due to the volume of these short runs. I know you get less to the gallon on short runs with a petrol engine and probably less also with a diesel engine but even with my driving pattern the diesel should be more economical.
I am also told that diesels are OK for going up and down motorways but not short journeys.
Surely with the new diesel engines (Merc or BMW) they cope with short journey economy ?
Any advice will be greatly appreciated.
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Forgot to mention - it will be an automatic.
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How much are you looking to spend on the car, and how long do you expect to keep it?
For argument's sake, you buy a Mondeo, getting 33 mpg as a petrol. Over four years you cover 30,000 miles. This means you use £3090 worth of petrol at £3.50 a gallon.
Or, you could have gone for a diesel. That would cost you £1,500 more, but you use less fuel. At 45 mpg, you spend £2,333 on petrol. Assuming servicing and insurance costs are the same - in reality they will marginally favour the petrol, if anything - the diesel needs to be worth about £800 more at the end of four years to make it a financially worthwhile investment, compared to leaving the money in the bank.
It might well be, but if you would rather drive a petrol than a diesel of similar power, get whichever one you prefer, but at your mileage, the financial difference is going to be minimal in relation to the overall running costs.
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How much are you looking to spend on the car, and how long do you expect to keep it?
From £20k + depending on used or new.
How long - at least 5 years.
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Have read a number of complaints that the new Mondeo tdci doesn't deliver the mpg that it should - no better than the petrol equivalent IIRC.
Tony
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Should be nothing wrong with using a diesel for short runs.
With a diesel you don't get the excess petrol put in by a choke and therefore the oil doesn't get washed off the cylinder walls when cold so much.
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Based on your mileage and the type of car you're after (from your other thread) I would agree with David HM. You will pay a premium for either a diesel Merc or BMW and that premium will buy you a lot of petrol! On your annual mileage I really don't think there will be a great saving to be made by switching to diesel (and I say that as an admirer of diesel engines!) It is easy to be seduced by fuel consumption figures but in reality, especially with a low annual mileage, other costs, particularly diesel purchasing premium and of course depreciation far outweigh fuel cost. But of course, if you prefer the driving experience, then of course go for it!
Baz
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Slightly off topic I suppose, but why do people say that servicing costs are higher for diesels? I have owned them for about 15 years now and apart from a couple of sets of new glowplugs have never had anything done to the engines themselves apart from oil every 5k - (but that's my choice). Exhausts also seem to last forever. Far better than the (old?) petrols where plugs, points and timing seemed to need changing every 5 minutes. So, my question is - where's the extra cost?
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Brian W brings up the most important point...these short runs will ruin a petrol engine but the diesel will be largely unaffected.
Diesels are brilliant on the short run cycle and the fuel consumption figures are at their very best compared with petrol. It is when cruising in 5th that a petrol vehicle can be gently driven to achieve impressive figures that close in on the diesel advantage.
On very short runs where a petrol was constantly in the warm up cycle, and only doing perhaps 27mpg, the diesel could get to 45-50mpg.
One of our vehicles is used for just the use you mention and when we changed to diesel three years ago our fuel costs dropped by a huge percentage....and I gave up worrying about the neat fuel washing oil from the bores!
It is true the low mileage will make the actual cost advantage less but overall the feeling will be the right car for the job.
MM
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If you enter 'Petrol or diesel for short runs' in the search box above, you will find the first item is a thread from last year with a lot of helpful posts.
You think you will cover just 6-7000 miles per year but you will be surprised how quickly the miles will mount up in retirement.
My situation is similar to yours and nothing would persuade me to go back to petrol.
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Ive run petrol engines for 30 years over short 5 mile trips and have never had a engine problem as a result, i may see a motorway once a month for a 3 mile stretch, and a longer journey 5 times a year. But still not cover more than 7.5k annually. There is no advantage to a diesel over the 1.8t petrol that i run.
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Forget all the arguments about saving 50p over the life of the car. Running cars costs money. Lots of it.
First, do you want a diesel? Some people (for reasons I can't fathom) do not. If you do, great, then go and buy one. If not go and buy a petrol.
If you look at a model range of cars there will be a range of engine sizes / power outputs - more power = more cost. You choose a car that suits your budget and driving expectations. If you want to go faster and / or drive a big car you pay more for a bigger engine / car and expect bigger fuel bills. Diesels are just an extension of this, you get a longer lived engine that gives bags more useable torque, and almost certainly uses less fuel. For this privelege you pay a bit more money, most of which you will recover when you come to sell it (or it dies about 100,000 miles after the petrol engine would have done).
Compared to the depreciation you're going to suffer on a £20k over 5 years at only 8k miles / year the difference in running costs will pale into insignicance.
Richard
PS unless you're a real 'boy-racer' the relaxed driving style offered by modern diesel engines is great, and you will wonder why you ever bothered with a petrol 'screamer'.
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Jud - yes, but how long do you keep your cars? This might not be a concern for you, but even if you don't see a problem, does the next owner, who's paid a premium for low mileage, really get value for money?
RichardW - I agree. A strictly utilitarian purchase to do this job would probably be a 2.0 Mondeo auto on an 02 plate for £9k. Even if it were literally worthless after 3 years, it would still have depreciated less than the BMW.
That doesn't mean I wouldn't spend the money on the BMW if I had it, but it does make quibbling over the marginal costs pretty pointless.
Drive them both, and anything else you might fancy. Take your time. Buy whichever one you like best, because neither is going to lose money in a Hyundai Sonata comedy fashion, both will be good to drive, economical, refined and safe.
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I had a change of job role recently. Instead of 800 miles a week on motorways I now commute a 12 mile round trip to the station 4 days out of 5. My Focus TDCi returned 37 mpg out of the last tank instead of the usual 44-46. Back on the m/way yesterday it ran really badly for the first 20-30 miles and then settled down again.
Oil consumption has also shot up since it has been on short journey duty.
Short trips are pretty bad for all engines I think.
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Why does oil consumption shoot up for short journeys?
All the cars I had were subjected to cold start and driven for 2 miles (home to lab) and 2 miles back in the evening. That accounts for 60% of the total mileage. They never used any oil between 5k oil change.
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"Why does oil consumption shoot up for short journeys?"
One explanation is that engines are made so that everything fits properly at working temperature. Until this is reached, pistons remains slightly oval and tolerances are wider, so oil is consumed faster. Having said that, it varies from engine to engine, and some seem to consume negligible oil whatever the circumstances (the converse is also true!).
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David usually i keep the cars no more than 5 years or 45k, enough time to kill the engine? However the last car i had is now my sons currently at 85k with only a mid exhast pipe changed the car is a 1996 primera 2slx and my son runs the car on short 6 mile commutes, with the 2 monlthy 2hour trip on the motorway. The highest milage i have ever accured is 110k over 7 years.
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Thanks everyone for your advice and comments.
Real good value and common sense as usual.
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"Why does oil consumption shoot up for short journeys?"
No idea but I have done 2 long m/way trips this week (150 mile round trip each time) and the oil consumption has been back to nil. Fuel consumption has been 42mpg and though the engine is as quiet as it was (a relative term given it's a diesel) it has very little get up and go.
Short trips, car on the blink, who knows?
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Fergus,
Sounds a bit odd. My wife's Xantia most weeks does a 2 mile commute and returns over 40mpg. On a motorway trip it will do over 50 (she drives at about 85mph - I always stick to 70!) In addition, in the 6000 miles she has done since she got it the oil consumption has been nil - it's still right on the max mark)
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Actually I've lost interest in the Focus. It's the best of the breed by far but I want to buy a decent car with a proper engine.
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I have just ordered a Volvo V70 D5 Auto. I have noticed that the fuel consumption figures for this diesel auto are considerably lower than the manual - e.g urban cycle 25.2 v 31.4 mpg. And that is much greate in proportion to the difference between the auto and manual petrol V70's (e.g 20.6 v 22. In fact the D5 manual is in a lower VED band.
why is this?
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Oldsinjun....Please let us know in due course what you settle for.
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