Running a diesel car

forgotmyname

I have a diesel and do lots of short journeys. It doesnt have a DPF so that is not an issue. I change the oil every 6 months or so and never do more than 8000 miles between oil changes.

You may save £250 a year on fuel, but how much will it cost to regenerate the DPF due to short journeys? When it regenerates it uses more fuel.

If the self regenerate fails then it can be costly to sort out.

Minrich

Petrol car is best for your use .... Diesel is cheaper than petrol now around where i live but i am still getting the wife a new petrol car to replace her diesel . Petrol small cars are nearly as efficient as diesels . No DPF issues either , which is a big expense and diesels will start to be hit tax wise as the cleaner diesel hype has been false and proven to be incorrect .

FreddieFrugal

Ok, I drive a modern (59 reg) diesel engined car (Focus). I've had it three years and during that time I've paid nothing extra for it other than standard servicing. No issues, car has occasionally decided to start trying to purge the DPF at inopportune times (as in, just finished a long journey, park car and it then decides to run its declogging routine) but most of the time it happens while I'm driving and isn't an issue.

Enjoyed strength of engine and good mpg. Averaged 55mpg during a week in Devon which seemed to somehow end up driving uphill every trip. Average in winter around here (flat area) 53-55. Average in summer low 60s

Now I'm relatively low mileage 10K-12K, which in theory means I'm not doing enough to warrant a diesel. Things is the vast majority of those miles are long journeys.

I work 3 days a week and do 40 miles round trip to work, straight driving very few stops. I then do one 4 mile round trip to weekly shop during week. The weekend will usually be 50 -> 100+ miles.

And the car is used for holidays.

For all other short trips we use the wife's Fiat 500 1.2 petrol.

So although my mileage is relatively low, the car is only used for regular long journeys. All town driving is done in the petrol and it seems to be very happy being used in this way.

From your description of driving you're doing mostly town driving with occasional long journeys (opposite of mine) you should have a petrol car. The apparent fuel saving will be wiped out at some point by an expensive fuel problem. To be honest in our experience around town the Petrol 500s mpg is very similar to the focus, it's on open roads that the Diesel engine makes a big difference.


EDIT: Also keep in mind that the Official MPG figures are not an accurate indication of real world mpg. Some cars have been found to get near to their figures, others are far far below. Sometimes the 'Eco' versions of cars which are supposed to get an extra 8 mpg or whatever over the regular version actually have barely any (if any) mpg advantage in real world driving.

You can't even use the figures to compare between manufacturers as some seem to be more or less accurate than others.

xHannahx

Hubby was doing about 10-12k town /countryside driving in a small diesel and the EGR went first clogged up with soot, got that fixed and dpf went not long after, very expensive for both. He has now gone back to petrol and whilst the fuel costs are higher, he has spent a lot less on servicing and repairs and maintenance. The diesel was 3-4 years old, the petrol he has now is 12 years old. Having a 12 year old petrol costing less per annum in repairs and maintanance makes no sense.

Also with newer diesels they like to destroy turbos. The 1.4 HDI used by PSA group a major offender. They are putting large turbos on small engines to get low emissions and the turbos aren't coping with the strain

Guys_Dad

Guysdad, why would you recommend occasionally filling up with Shell V plus?

Try googling "v plus honest john". You will see his technical reasons. In fact he recommends always using V plus 100% of the time.

In fact, see here http://www.honestjohn.co.uk/askhj/answer/41641/is-v-power-suitable-for-use-in-my-skoda-octavia-

dcouponzzzz

Not that it will be of value to you, but I picked up a 4 yr old polo 1.2 bluemotion a few weeks ago for 7k. It had done 42k miles and from the looks of it, it hadn't been run out on long journeys much at all. Previous owner has replaced EGR and the DPF has had a yearly replacement (and 6 gaskets.... ).

I'm more than happy myself as I've just hit 450 miles on the first half tank using premium diesel from Costco. 1 trip a week I get 70mpg at 70mph on the motorway, the other 4 days I trundle along at 55mph and average 80-85mpg. Compared to my previous car I've halved my costs (55quid a week previously, 25-30 now). I average 14k on motroway journeys and add another 3k annually for run arounds.

FreddieFrugal

I find this interesting, so I've done some calculations using as much information as I could gather. For two cars the difference in yearly cost between a Diesel and Petrol version (P or D from now on.)

Based everything on 9000 miles a year.

I used auto trader and selected the cheapest P/D car available in the same trim levels and age for the particular make and model.

I used the AA report on average fuel prices for the last month to work out fuel costs for each car. i also used an AA report on car running costs to work out costs of servicing per mile parts and labour 4.46ppm/4.57ppm (P/D)

I used moneysupermarket to find cheapest 5 star defaqto cover available for car assuming 9000 miles a year. All variables kept the same except car type. Churchill was cheapest for each vehicle.

When you see my results for fuel costs and mpg I put two figures separated by a / the first figure is using the official combined mpg as given by manufacturer. The second is based on the average user submitted mpg figures taken from Honest John website.



First car - Ford Fiesta 12reg Zetec trim - 1.2L P and 1.4L D

P - Cost £6394 - mpg 51.4/41.0 - tax £30 - insurance £387 - Years fuel £932.92/£1169.57 - servicing £401.40 = total £1741.72/£1979.37

D - Cost £6970 - mpg 68.9/54.7 - tax £20 - insurance £417 - Years fuel £710/£894.59 - servicing £411 = total £1558/£1742.59

P - D = yearly saving of £183.72/£236.78

Number of years required to recoup increased cost of vehicle = 3.13/2.43



Second car - Skoda Octavia 12 reg - SE trim - P 1.2 TSI - D 1.6 TDI

P - Cost £7350 - mpg 49.6/45.8 - Tax £130 - insurance £447 - years fuel £966.78/1046.99 - servicing £401.40 = total £1945.18/£2025.39

D - Cost £9480 - mpg 62.8/56.7 - Tax £30 - insurance £506 - Years fuel £779.21/£863.04 - servicing £411 = total £1726.21/£1810.04

P - D = yearly saving of £218.97/215.35

Number of years required to recoup increased cost of vehicle = 9.73/9.89


So, fiesta was a funny one because could get diesel for not much more than the petrol. Octavia different story. Basically the fiesta would take 3 years before you made any saving, Octavia nearly 10 years. Most diesel versions do tend to cost at least £1000 more than petrol equivalent so you're looking at about 4 - 5 years before you're actually making a saving.

A lot depends on how long you plan to keep it or whether you're likely to sell on again quickly.

Also add the fact that at your mileage and town driving you're more at risk of encountering DPF problems. One failure of those systems and you'll have wiped out years worth of fuel and tax savings.

I didn't include depreciation as that would have given me a headache. It generally slows down dramatically after 3 years though.

flamin_galah

Thanks for all the replies, a bit of a mixed response though I think leaning towards a petrol being better. Guy's Dad, thanks for the link to the Shell V-plus info.

I'm not concerned about the initial price with regards to it being £500 more for a diesel etc because it's a gift and the giver has said there's some flexibility there. I'm not concerned about depreciation as I tend to buy cars and keep them - I bought my current car at 5 years old and is now 12 years old. It's only in the last year or so that it's been a money pit so it's definitely time for a switch.

Running costs are the biggest factor to me which is why the diesel thing was something to consider. I'm still unsure about it, with this DPF thing so I will use that to research individual models and the likelihood of DPF problems with them before making a proper decision.

IanRi, interesting that you say that about driving a Focus as that's one of the models we're considering now as I need something with a decent bootspace and the Corsa/Fiesta size range I was previously looking at just isn't quite big enough. Which rules out the really efficient small petrol cars.

Thanks for the tip on looking for user MPGs at Honest John, I'd just been going off the ones on the Autotrader ads, which are the official ones I believe. I did some fuel cost calculations but I used the current 115.9p for petrol round here and 120.9p for diesel (which is much higher than currently is but reflects the typically higher price of diesel which I'm sure will reinstate soon enough) and that's how I got the £250 cheaper running costs. Obviously, this is worthless if I'm going to be hit with DPF repairs, so as I said above I'll look into that more closely.

As with everything, sometimes it's just luck isn't it? My dad has two diesel vehicles, one of which only ever does shortish trips, the longest being an occasional 20 min run down a dual carriageway and he has no problems with his DPF. The other does some longer runs but still probably similar to what I do and again no DPF issues, so he's pushing me towards a diesel, but I wouldn't be driving the types of cars he has so he might just be lucky with the models he's got.