DPF (Diesel Particulate Filter) Question

hertz

Hi
I'm planning on buying a new used car early next year. I currently do 8k miles a year. Most of my driving is town with some long distance driving every other weekend.
I have a concern about the DPF's fitted to newer diesel cars getting clogged up for drivers who don't drive the car for long enough jopurneys.
If I was to buy a diesel car with a DPF and do mostly town driving how often would I need to drive the car on a long journey to clean out the filter?

colm_mcm

Buy a hybrid, or a petrol, but diesel not worth it

Max Power1

Buy a petrol!

bazz26

Imo if you have to ask how often you need to drive a diesel car on a long journey so that the DPF can regenerate then it says to me that you don't have a need for a diesel car.

A hybrid like a Prius, Insight or Civic IMA sounds like it would suit your usage better. The electric motor is suited to city driving, will be more frugal and no turbo, DMF or DPF failure to worry about.

Mar4ix

if you want particularly diesel car.... and it with dpf, you may get it removed and remap ecu. cant remember who doing this, but lads will point you.
i think, that wouldnt cost an arm and leg.

but my opinion is.... petrol would more suitable for your needs.

Glenvw

Diesel car will only benefit you if you we're doing more mileage. As previous post you can get filter removed. Regeneration for particulate filter only take place when car is at a higher speed so city driving would not allow regeneration to take place

vectra

I have been driving diesels mostly around town with over 4 years,
Never had a problem with them, When possible keep revs between 2 & 2.5k.

Del2005

hertz wrote: »

Hi
I'm planning on buying a new used car early next year. I currently do 8k miles a year. Most of my driving is town with some long distance driving every other weekend.
I have a concern about the DPF's fitted to newer diesel cars getting clogged up for drivers who don't drive the car for long enough jopurneys.
If I was to buy a diesel car with a DPF and do mostly town driving how often would I need to drive the car on a long journey to clean out the filter?

IIRC 20 to 30 minutes of motorway driving, once you open it up, a week will keep the DPF ok. But your mileage doesn't warrant the premium for the diesel. Better off in a hybrid or petrol and then you don'thhave to worry about the DPF.

Zubeneschamali

bazz26 wrote: »

A hybrid like a Prius, Insight or Civic IMA sounds like it would suit your usage better.

How long would it take to pay back the cost of a hybrid over a similarly powerful petrol at 8K miles a year?

Golf 1.2 TSi 5 door 105 bhp: €23K.
Auris Hybrid €25.5

So, 8000 miles at 35 mpg in the Golf: 1044 litres = €1672
and in the Auris Hybrid at 50 mpg: 731 litres = €1170

So about €500 extra, so your €2500 investment will take 5 years to pay back (ignoring finance).

September1

Zubeneschamali wrote: »

How long would it take to pay back the cost of a hybrid over a similarly powerful petrol at 8K miles a year?

Golf 1.2 TSi 5 door 105 bhp: €23K.
Auris Hybrid €25.5

So, 8000 miles at 35 mpg in the Golf: 1044 litres = €1672
and in the Auris Hybrid at 50 mpg: 731 litres = €1170

So about €500 extra, so your €2500 investment will take 5 years to pay back (ignoring finance).

If you go LEAF which is 26.5 then you would save 1512 pa vs Golf and 1010 vs hybrid, so you need just above two years to pay off difference to Golf in fuel costs. When you start car with cold engine the economy is not so great, so for short drives with time to cool engine in between economy would be much lower then advertised.

Things is OP is rational and buying a petrol car does not make sense in Ireland, as depreciation would be much harsher than on diesel, which would be cheaper regardless of how many miles he does per year. He could just remember to drive it at higher speeds once a week, take care of turbo etc

Zubeneschamali

September1 wrote: »

Things is OP is rational and buying a petrol car does not make sense in Ireland, as depreciation would be much harsher than on diesel, which would be cheaper regardless of how many miles he does per year.

The % depreciation may be lower on a diesel, but they cost more, and the actual depreciation in cash money terms is likely similar.

Also: 2nd hand buyers are eventually going to learn that low-mileage turbo-diesels are a bad buy, which will increase depreciation on them as folks factor in a €2K DPF replacement.

Zubeneschamali

September1 wrote: »

When you start car with cold engine the economy is not so great, so for short drives with time to cool engine in between economy would be much lower then advertised.

Much lower than the 35 mpg I proposed?

September1

Zubeneschamali wrote: »

The % depreciation may be lower on a diesel, but they cost more, and the actual depreciation in cash money terms is likely similar.

I somehow think that it is way easier to sell diesel those days, but OTOH premium for diesel is much higher than it used to be, so I think you might be right.

Zubeneschamali wrote: »

Also: 2nd hand buyers are eventually going to learn that low-mileage turbo-diesels are a bad buy, which will increase depreciation on them as folks factor in a €2K DPF replacement.

This would be totally reasonable, but it still did not happen. I really wish that 2009 - 2011 petrol cars owners would suddenly be in possession of very prized vehicles, but I'm doubtful it would happen. There are couple reasons, first is you can pass NCT without DPF so currently it seems better to just remove this part from car and remap engine - although insures could be unhappy with that. Second is that most of Ireland is rural, and with longer distances driven, this problem would not manifest itself too fast. Another is that low-mileage vehicles command a premium anyway, so even if DPF if deducted they could still do pretty well.

Zubeneschamali wrote: »

Much lower than the 35 mpg I proposed?

It could be, I have some details for basic Octavia 1.6 petrol on cold day:
first few hundred meters is around 5 mpg, then after two kilometers 17mpg, then after 3 kms 20mpg, then in long distance drives it can reach 53 mpg.

I wonder if some OP with diesel car could do it for us, and next time we have a cold spell reset average consumption counter and let us know his results after couple of distances in the morning - I have suspicion that diesels may suffer less.

bazz26

vectra wrote: »

I have been driving diesels mostly around town with over 4 years,
Never had a problem with them, When possible keep revs between 2 & 2.5k.

With all due respect, how many of your cars came with a DPF, the first vRS? And you buy new and change every 2 years iirc, thats hard to gauge on the reliability of the DPF. The next owner could be the one experiencing the issues however.

bazz26

Zubeneschamali wrote: »

How long would it take to pay back the cost of a hybrid over a similarly powerful petrol at 8K miles a year?

Golf 1.2 TSi 5 door 105 bhp: €23K.
Auris Hybrid €25.5

So, 8000 miles at 35 mpg in the Golf: 1044 litres = €1672
and in the Auris Hybrid at 50 mpg: 731 litres = €1170

So about €500 extra, so your €2500 investment will take 5 years to pay back (ignoring finance).

I wasn't getting into the financial side of it to be honest as it's a broken record at this stage. I was just giving the OP a more suitable alternative to a diesel for city driving.

vectra

bazz26 wrote: »

With all due respect, how many of your cars came with a DPF, the first vRS? And you buy new and change every 2 years iirc, thats hard to gauge on the reliability of the DPF. The next owner could be the one experiencing the issues however.

With all due respect the original question was about dpf and not multiples so what difference does it make?

I also have Printed evidence that my dpf in my last car was 100% perfect prior to selling the car. That was after 2 years of almost constant stop/start town trips.

Now how is that hard to gauge the reliability of a dpf.

bazz26

vectra wrote: »

With all due respect the original question was about dpf and not multiples so what difference does it make?

I also have Printed evidence that my dpf in my last car was 100% perfect prior to selling the car. That was after 2 years of almost constant stop/start town trips.

Now how is that hard to gauge the reliability of a dpf.

Yes, the question and topic were about DPFs and you stated that you are driving diesels around town for 4 years without any issues which suggests to me that you have driven a diesel with a DPF for 4 years around town with no DPF issues?

Also I'm genuinely curious to know how the condition of the DPF is recorded other than it is function normally as logged by the ECU? The reason I ask is that in my last car when my DPF was replaced the only ECU fault codes logged were around failed regeneration cycles just prior to the car going into limp mode. It was only when they removed the DPF and examined it that they seen the extent of the sut blockage.

vectra

bazz26 wrote: »

Yes, the question and topic were about DPFs and you stated that you are driving diesels around town for 4 years without any issues which suggests to me that you have driven a diesel with a DPF for 4 years around town with no DPF issues?

Also I'm genuinely curious to know how the condition of the DPF is recorded other than it is function normally as logged by the ECU? The reason I ask is that in my last car when my DPF was replaced the only ECU fault codes logged were around failed regeneration cycles just prior to the car going into limp mode. It was only when they removed the DPF and examined it that they seen the extent of the sut blockage.

a vag mechanic buddy of mine did a scan with vcds before I sold it,

hertz

OP here,
Thanks for the feedback so far.

Bazz26, you mentioned you got your DPF changed on one of your cars. Do you mind I ask, what car was it and was it expensive?

bazz26

hertz wrote: »

OP here,
Thanks for the feedback so far.

Bazz26, you mentioned you got your DPF changed on one of your cars. Do you mind I ask, what car was it and was it expensive?

A Volvo S40 and it cost me the bones of €1k. Of course they can be removed altogether these days for alot less money but imo sooner or later the NCT will start including these in their emmissions tests.

vectra

bazz26 wrote: »

A Volvo S40 and it cost me the bones of €1k. Of course they can be removed altogether these days for alot less money but imo sooner or later the NCT will start including these in their emmissions tests.

But there no Emissions test on a diesel. it is a smoke test. If they do bring in the dpf test i reckon it will only be a visual test.