Diesel + average mileage + DPF = bad idea?

DeepBlue

Looking for some advice from those more knowledgeable than I.

A relative is after putting down a deposit on a 171 Volvo v40 Momentum Diesel and has now read up a bit about DPF and wants to cancel the deal. She's due to pick up the car next week and finalise finance.

Her daily mileage to/from work would, at a guess, be less than 20K. Every few weeks she'd probably do 100-150K trips on the weekend. I'd guess maybe once every 3 weeks or so.

In this scenario is she better off backing out of the deal and going for petrol or sticking with it?

bazz26

What does that mileage consist of though? If it's mainly city type driving with alot of short stop/start journeys then a diesel is pointless and potentially going to cause more issues long term. If her mileage is mostly long runs or motorway driving then it won't be a problem but at that mileage I still would consider petrol or hybrid options.

DeepBlue

bazz26 wrote: »

What does that mileage consist of though?

No motorway driving. Long runs would be intermittent - probably averaging once every three weeks. Dunno if this would be enough to clear the DPF.

So I guess DPF is still an issue even on new diesels. Her preference would have been for petrol but they seem to be pretty rare to find these days.

Leonard Hofstadter

It's not how much you drive them it's where you drive them. You could drive one just 2,000 miles a year and have no problems at all, ever. What diesels do need is high speed blasts to keep the DPF happy. That said, some engines are more prone to the filter getting blocked than others.

ofcork

My work run is around 20k each way and give the car a run every couple of weeks have a 12 avensis diesel and no problems in 3 years of ownership.

Shefwedfan

In reality based on her mileage he/she would be better backing out and looking at hybrid or full electric. For the money she is paying she could get a new eGolf which will go circa 220-240km per charge. The daily commute would only require a full charge per week. The eGolf would be similar in term of style/comfrot to the V40. If Tesla 3 was out they could maybe have looked at that

BMW i3 could be another option.

Hybrid would mean most days he/she will be able to travel to work mostly using battery. Toyota is probably too big of a drop down from Volvo. So I would look at Lexus. CT200 is similar size.

Volvo themselves have admitted in a few years they will be all hybrid/electric.

That is all based on been able to back out of the deal itself from the garage. I would guess if they have put down deposit then they are kind of screwed.

bazz26

OP, ask her to have a look at the Lexus CT200h petrol/electric hybrid. It's similar in size to the V40. Has the same running gear as the Toyota Prius but is aimed more upmarket.

bazz26

Also it should be noted that the newer DPFs are not near as much of an issue if doing short trips as when they came out first which is where all the scaremongering about DPFs comes from.

bazz26 wrote: »

What does that mileage consist of though? If it's mainly city type driving with alot of short stop/start journeys then a diesel is pointless

Diesel is cheaper to buy than petrol and even on short trips will be more economical than a petrol so I wouldn't call it pointless.

bazz26

Well that's amazing as any time I drive around town my diesel car gives **** fuel economy from all the stopping and starting but what would I know. And there is no guarantee that diesel will be cheaper to buy than petrol in the mid to long term.

bazz26

bazz26 wrote: »

Well that's amazing as any time I drive around town my diesel car gives **** fuel economy from all the stopping and starting but what would I know. And there is no guarantee that diesel will be cheaper to buy than petrol in the mid to long term.

Well what ever economy you are getting from your diesel an equivalent petrol will be worse and you also have to factor the cost of diesel being lower into the calculation.

I also don't really believe you are getting that bad an economy considering the we have one newish diesel in the household and 90% of its trips are short city trips in traffic and its averaging around 50mpg. Another diesel in the family has about 75% of its trips being short city trips and the rest long motorway trips and thats getting over 55mpg.

Leonard Hofstadter

Diesels take forever to warm up (compared to a petrol) so if you only do short distance journeys there won't be any fuel savings.

Larbre34

bazz26 wrote: »

Well that's amazing as any time I drive around town my diesel car gives **** fuel economy from all the stopping and starting but what would I know. And there is no guarantee that diesel will be cheaper to buy than petrol in the mid to long term.

Without giving us your engine specs that doesnt tell us much on its own, but its fair to say a non hybrid petrol of similar output will have worse economy than a diesel, even around town.

You are correct about there being no guarantee around diesel prices, but seeing as it still underpins the economy and the Govt swerved an opportunity to close the duty gap in any sense in next years budget, im not concerned about it losing its financial advantage anytime soon.

Yes diesels are pricier to buy new, but for anything at or over average mileage there is little in Ireland to beat a quality second hand diesel of a common model. Let someone else take the showroom hit. Lexus may say diesel is dead, and they would to suit their own purposes, but they are wrong.

captainspeed

captainspeed wrote: »

Diesels take forever to warm up (compared to a petrol) so if you only do short distance journeys there won't be any fuel savings.

This simply is not true.

Wailin

She'll be fine. I think there's a bit of hysteria around the dpf filter. 20k per year is plenty.

Edit: Oops need to wake up, read that 1st post wrong!

BlazingSaddler

I bought a Grand CMax 1.6 diesel back in early 2012, very soon after my work situation changed from doing long motorway runs to short daily stop start runs. I was very concerned and thought long and hard about changing to Petrol but couldn’t really afford the change, I even posted here asking the same question. Long and short of it, I still have the car now, average 12,500 per year and have never had a problem with it. I do keep it regularly serviced.

Audioslaven

It really depends on your driving. If you are giving the car at least a 20/30 minute consisting driving every week, it should keep the filter clean. When you give it this spin, don't be afraid to drive it on keeping revs up at around 2K.

We have a mazda 3 1.6 with 110 miles on it and the dpf has been working fine. It gets a good spin each weekend with the kids for swimming etc (30 min). I did take it out 5k miles ago and wash it out as it was giving a silence ECU error. Since that, it has been going great and no errors but it has been pretty trouble free since I bought it at a year old. The car will be 10 years next year on the original dpf so if I need to put in a new one so be it.

professore

Have an 05 focus 1.6 HDi with nearly 300k Kms on it and give it a motorway run once a month and never once had a DPF issue. Consistent 50 - 55 mpg mixed driving, more on a run. Mechanic keeps saying they are a crap engine that could blow anytime but I service it regularly and so far so good. No way could you get that from a petrol.

bazz26

professore wrote: »

Have an 05 focus 1.6 HDi with nearly 300k Kms on it and give it a motorway run once a month and never once had a DPF issue. Consistent 50 - 55 mpg mixed driving, more on a run. Mechanic keeps saying they are a crap engine that could blow anytime but I service it regularly and so far so good. No way could you get that from a petrol.

Does your Focus have a DPF as they were not standard on diesels back then? I had a 06 Volvo S40 at one time with that very same engine that needed a new DPF under my ownership.

Toyotafanboi

A high speed run isn't necessary for DPF regeneration, all it needs is a consistent speed, a couple of minutes in second or third at 40/50kmh is more than adequate.

I wouldn't be one to defend diesel but a modern car will be able to get itself to regen in a lot more variable driving conditions than a car where a DPF was an emerging technology a decade ago.

Shefwedfan

Ronald Repulsive Treason wrote: »

Well what ever economy you are getting from your diesel an equivalent petrol will be worse and you also have to factor the cost of diesel being lower into the calculation.

I also don't really believe you are getting that bad an economy considering the we have one newish diesel in the household and 90% of its trips are short city trips in traffic and its averaging around 50mpg. Another diesel in the family has about 75% of its trips being short city trips and the rest long motorway trips and thats getting over 55mpg.

I always laugh at the magical numbers people post here in regards to the MPG or ltr/100km they are getting from there diesel. It is all BS....

So you are trying to say you are doing 5.5ltr/100km? If so your car is magically....

I have driven many many diesels. I still have one. My A6 which was 11 was doing 20 MPG-14ltr/100km in city driving, It was a heavy on juice

Majority of other diesels are at 7-8ltr/100km. Which at best is 40mpg.

For motorway driving in A6 it was 55MPG and it was great.

It is funny how much people love daysel they make up numbers. A hyrbid in town will get way better MPG than a diesel. If it didn't why would the manufacturers spend millions inventing it?

Shefwedfan

Shefwedfan wrote: »

I always laugh at the magical numbers people post here in regards to the MPG or ltr/100km they are getting from there diesel. It is all BS....

So you are trying to say you are doing 5.5ltr/100km? If so your car is magically....

I have driven many many diesels. I still have one. My A6 which was 11 was doing 20 MPG-14ltr/100km in city driving, It was a heavy on juice

Majority of other diesels are at 7-8ltr/100km. Which at best is 40mpg.

For motorway driving in A6 it was 55MPG and it was great.

It is funny how much people love daysel they make up numbers. A hyrbid in town will get way better MPG than a diesel. If it didn't why would the manufacturers spend millions inventing it?

I'm not lying, 5.6L/100km is the long term average consumption and the car does a 10km return city trip daily with about half of it in stop/start traffic. Why would I lie?

I don't believe your number they are totally off with my own experience and basically any other information on the topic.

ofcork

I must say my avensis stays around 7.5 to 8 in mixed driving best I have seen was 4.2 on a trip to Waterford from cork.

Shefwedfan

Ronald Repulsive Treason wrote: »

I'm not lying, 5.6L/100km is the long term average consumption and the car does a 10km return city trip daily with about half of it in stop/start traffic. Why would I lie?

I don't believe your number they are totally off with my own experience and basically any other information on the topic.

Of course the numbers are correct ....I just doubt them as most manufacturer would not even attempt to say that is there consumption numbers....seems like you have one of the many magical cars that exist in Ireland

It is constant on here about the numbers people come up with to say diesel is great. It seems Ireland is ideal conditions for diesel compared to every other country on the planet. It is strange every manufacturer is not coming here to do there testing,....

You don't have to believe my numbers, no skin off my nose. Mine are real numbers based on many many miles driven in diesel. As I said diesel is perfect for motorway driving. City driving it isn't.

Every other country in the World knows this, the Irish seem to have mental block about it

acronym Chilli

Maybe the green diesel is better

DeepBlue

Thanks for all the replies.

I don't think an electric-only car would work for her as she occasionally needs to use the car for work and such journeys would be unpredictable and could be long so range-anxiety would be an issue especially if the car isn't fully charged and she wouldn't have the luxury of stopping at a recharging point for 30 minutes. If that weren't the case I think an electric car would suit although they seem to depreciate very quickly.

She's kept her current car from new for the last 13 years with a mileage of 160K miles so about 12,500 miles or 20K kilometres per year.

Her driving profile would be from just outside town (rural) into town and back home and wouldn't really be stop/start in nature for the most part. If all it takes to regen the dpf is approx 30 min of 60kph then I'm sure that she'd be doing that in the course of each week with ancillary driving so it sounds like she'd be ok.

The Volvo she's getting is approx 6 months old with about 20K on the clock for just less than 24K which seems like a reasonable deal.

J.pilkington

BlazingSaddler wrote: »

I bought a Grand CMax 1.6 diesel back in early 2012, very soon after my work situation changed from doing long motorway runs to short daily stop start runs. I was very concerned and thought long and hard about changing to Petrol but couldn’t really afford the change, I even posted here asking the same question. Long and short of it, I still have the car now, average 12,500 per year and have never had a problem with it. I do keep it regularly serviced.

I think this is a great post. Dpf along with dmf are two words that armchair experts both on boards and in the pub love to preach about even though they know jack all about them outside of the stories that other armchairs experts told them but yet have no problem giving advice as if they are mechanics themselves

J.pilkington

Shefwedfan wrote: »

I always laugh at the magical numbers people post here in regards to the MPG or ltr/100km they are getting from there diesel. It is all BS...

Funny stuff starting a post with that then doing the exact same thing!

The Bishop Basher

J.pilkington wrote: »

I think this is a great post. Dpf along with dmf are two words that armchair experts both on boards and in the pub love to preach about even though they know jack all about them outside of the stories that other armchairs experts told them but yet have no problem giving advice as if they are mechanics themselves

This X100

OP - I’ve owned many diesels doing small mileage and I’ve never had an issue. As many have stated here, it’s the type of driving that’s more important as opposed to distance travelled.

The amount of nonsense spouted by people who have no direct experience and just regurgitate the same aul ****e about diesels that they’ve heard on here is unreal.

None of my diesels take “forever” to warm up. Even the older ones are up to opeeating temp within a frew minutes so that line is nonsense. They don’t cost any more to service or maintain so that line is equally nonsense. And as someone else has already stated, they are far more economical then petrol in ALL driving conditions on top of which, diesel costs less at the pump so they are more economical in every way..

To be blunt about it, the vast majority of people on here who knock diesel haven’t a rashers what they’re talking about and are just regurgitating the same group think line they heard someone else spout yesterday as they think it makes them sound knowledgeable..

Problem is they’re talking bollox..

Tell your relative to go ahead with the purchase and enjoy the be motor. I hope they have many miles of happy and safe driving..

Toyotafanboi

Well some of that is slight bias too.

For example, out 2016 Diesel Golf takes about 5kms to be up to temp (according to the dash) from a cold start, my petrol Civic only takes around 2kms on the same route to be up to temp.

The lifelong average MPG of the 1.6 diesel Golf is 5.4l/100km, the lifelong average of the Civic 1.8 Petrol is 6.1l/100km so an average cost difference of around €1 over 100kms.

The higher maintenance on diesels arguement seems to stem from higher failure rates of DPF and DMF's. These failures do seem to be less common than they were a decade ago, that's a certainty but at the same they do happen, make no mistake over that. That and injector and EGR failures can and do frequently happen and all of these issues are more likely on cars that do short trips. You are almost 100% not going to get any of those issues from a petrol car.

That and the fact that if you do short trips why would you want to do them in a car with a less refined engine? When our Golf diesel was in for a service we had a petrol replacement car and I couldn't care less but my car ignorant missus couldn't believe how "smooth" it was compared to hers and her car must be worn out. No, it was just a new petrol engine vs a 1 year old diesel. You'd hardly tell that the petrol engine was running.

Casati

Toyotafanboi wrote: »

Well some of that is slight bias too.

For example, out 2016 Diesel Golf takes about 5kms to be up to temp (according to the dash) from a cold start, my petrol Civic only takes around 2kms on the same route to be up to temp.

The lifelong average MPG of the 1.6 diesel Golf is 5.4l/100km, the lifelong average of the Civic 1.8 Petrol is 6.1l/100km so an average cost difference of around €1 over 100kms.

The higher maintenance on diesels arguement seems to stem from higher failure rates of DPF and DMF's. These failures do seem to be less common than they were a decade ago, that's a certainty but at the same they do happen, make no mistake over that. That and injector and EGR failures can and do frequently happen and all of these issues are more likely on cars that do short trips. You are almost 100% not going to get any of those issues from a petrol car.

That and the fact that if you do short trips why would you want to do them in a car with a less refined engine? When our Golf diesel was in for a service we had a petrol replacement car and I couldn't care less but my car ignorant missus couldn't believe how "smooth" it was compared to hers and her car must be worn out. No, it was just a new petrol engine vs a 1 year old diesel. You'd hardly tell that the petrol engine was running.

Most new petrols have turbo’s, dmf’s and other stuff to go wrong too.

Your Civic is economical but when you take your actual l/100km and take account of the cheaper diesel pricing the Civic would be over 30% more expensive to fuel

xl500

bazz26 wrote: »

OP, ask her to have a look at the Lexus CT200h petrol/electric hybrid. It's similar in size to the V40. Has the same running gear as the Toyota Prius but is aimed more upmarket.

This A bulletproof Car

Casati

DeepBlue wrote: »

Looking for some advice from those more knowledgeable than I.

A relative is after putting down a deposit on a 171 Volvo v40 Momentum Diesel and has now read up a bit about DPF and wants to cancel the deal. She's due to pick up the car next week and finalise finance.

Her daily mileage to/from work would, at a guess, be less than 20K. Every few weeks she'd probably do 100-150K trips on the weekend. I'd guess maybe once every 3 weeks or so.

In this scenario is she better off backing out of the deal and going for petrol or sticking with it?

This car has a rrp of 31k, exactly the same price as the petrol V40 with the same power so petrol really makes limited economic sense, the diesel will be cheaper to fuel and tax, despite all the bs the govt laid out their views and didn’t touch diesel in the budget too

Getting a 171 for 24k is a good deal too so she hasn’t much to worry about

dil999

Toyotafanboi wrote: »

Well some of that is slight bias too.

The lifelong average MPG of the 1.6 diesel Golf is 5.4l/100km, the lifelong average of the Civic 1.8 Petrol is 6.1l/100km so an average cost difference of around €1 over 100kms.

Based on the numbers you gave above and on average petrol/diesel prices its €1.76 per 100Km. Not €1. And I think you are taking an exceptionally efficient petrol car in your comparison. I would suggest after a quick look at "Fuelly" for a petrol golf, 7l/100km would be a more reasonable estimate. That would make the difference €2.93 per 100Km. For the average annual mileage of 16000Km thats €470 per year.

Edit:
I did a quick look on https://www.spritmonitor.de/
Its an excellent site, and much easier to use than Fuelly.

Perhaps your Civic is not that exceptional, the average for a Golf petrol 2014-2017, 100-120PS comes out at 6.3L/100km, the diesel equivalent comes out at 5.3L/100km. So based on average petrol / diesel prices you are looking at €2.10 per 100km. which is €336 per year.

duffman3833

its ridiculous that dealers don't ask what mileage you do and recommend which engine would suit. Its all getting the best sale, no interest in anything else

acronym Chilli

dil999 wrote: »

Based on the numbers you gave above and on average petrol/diesel prices its €1.76 per 100Km. Not €1. And I think you are taking an exceptionally efficient petrol car in your comparison. I would suggest after a quick look at "Fuelly" for a petrol golf, 7l/100km would be a more reasonable estimate. That would make the difference €2.93 per 100Km. For the average annual mileage of 16000Km thats €470 per year.

Edit:
I did a quick look on https://www.spritmonitor.de/
Its an excellent site, and much easier to use than Fuelly.

Perhaps your Civic is not that exceptional, the average for a Golf petrol 2014-2017, 100-120PS comes out at 6.3L/100km, the diesel equivalent comes out at 5.3L/100km. So based on average petrol / diesel prices you are looking at €2.10 per 100km. which is €336 per year.

Which leads on to purchase price differentials...
...configuring a VW Golf today, the price difference between the base petrol (1.0TSI, 63kW) and base diesel (1.6 TDI, 66kW) is €2455 (configuring a 5 door trendline). The quoted fuel efficiency figures for those two today are 4.8 and 4.1 l/100km, and only 2 gCO2 in the difference.

So even without discounting, if the diesel saved €336 per year it would take 7.3 years to pay off. If the difference between the two has narrowed further as indicated by the current efficiency figures, then that saving is even smaller and payback longer.

Finally, given that at the same power-output, the VW petrol engine is just 1l and the diesel engine 1.6, it's of interest that a 1.0l engine will tend to use less fuel in urban/stop-start driving and idle than a large engine. That may however be mitigated by things that some of the most recent engines do like disabling certain cylinders, stop-start, and so on.

bazz26

duffman3833 wrote: »

its ridiculous that dealers don't ask what mileage you do and recommend which engine would suit. Its all getting the best sale, no interest in anything else

But that's a salesperson's job, sell you what they have even if it's something you don't really want. Buyers should educated themselves enough to know what they want or need, not what the salesperson thinks they should. Buyers should not have to be held by hand in a showroom like a child. We as a nation are too easy to claim it was someone else's fault when it comes to spending money unwisely otherwise nothing is learned from the Celtic Tiger.

acronym Chilli

bazz26 wrote: »

But that's a salesperson's job, sell you what they have even if it's something you don't really want. Buyers should educated themselves enough to know what they want or need, not what the salesperson thinks they should. Buyers should not have to be held by hand in a showroom like a child. We as a nation are too easy to claim it was someone else's fault when it comes to spending money unwisely otherwise nothing is learned from the Celtic Tiger.

I agree (very strongly!) with most of what you say, I've put it in bold.
However, the bit I've put in italics I'd take partial issue with. It's true in the short term, but over the long-term other models can work. Real long term success can be built on a more win-win approach and trying to sell people what they really want/need.

Granted, as a sales-person you could lose your job while trying to get that process started, however I've seen people do well in sales by taking a more customer-centred approach. The pay-off came in terms of repeat sales, third party recommendations, and once a degree of trust was built-up, more streamlined sales process and steady margins.

However, coming back to the text I bolded: you're dead right that as a buyer you've got to start off assuming that the salesperson is trying to sell you what they've got to sell today, and is in a zero-sum type mode where they want to pick you up by your ankles and shake you until all your change falls out!

dil999

acronym Chilli wrote: »

Which leads on to purchase price differentials...
...configuring a VW Golf today, the price difference between the base petrol (1.0TSI, 63kW) and base diesel (1.6 TDI, 66kW) is €2455 (configuring a 5 door trendline). The quoted fuel efficiency figures for those two today are 4.8 and 4.1 l/100km, and only 2 gCO2 in the difference.

So even without discounting, if the diesel saved €336 per year it would take 7.3 years to pay off. If the difference between the two has narrowed further as indicated by the current efficiency figures, then that saving is even smaller and payback longer.

Finally, given that at the same power-output, the VW petrol engine is just 1l and the diesel engine 1.6, it's of interest that a 1.0l engine will tend to use less fuel in urban/stop-start driving and idle than a large engine. That may however be mitigated by things that some of the most recent engines do like disabling certain cylinders, stop-start, and so on.

My reply was a specific reply to someone else's comment on average fuel efficiency. You are correct that for the equivalent golf models, the petrol is cheaper, but that's not the case for all manufacturers, the Volvo V40 (the OPs car), T2 petrol and D2 diesel are identically priced.

Obviously if you are comparing overall cost saving then you have to look at all potential costs, fuel consumption savings is just one. At the moment, for equivalent model with equivalent PS, the diesel will always be more fuel efficient for normal driving conditions. It sometimes costs more to purchase.

I doubt there is currently much research being put into diesel engine technology, so we will probably see other technologies overtake diesel in terms of fuel efficiency over the next number of years.

Leonard Hofstadter

Casati wrote: »

Most new petrols have turbo’s, dmf’s and other stuff to go wrong too.

Your Civic is economical but when you take your actual l/100km and take account of the cheaper diesel pricing the Civic would be over 30% more expensive to fuel

DMFs don't go wrong in petrols, it's a complete non-issue in them. There's no particulate filters in them either (although that will soon change).

Petrol engines don't need DMFs because they are so much smoother running than diesels - that after all is the whole point of a DMF, to reduce the roughness and vibrations the driver experiences through the pedals. As petrol engines are much smoother running they don't put the DMF under any strain hence why it is extremely unusual for one to fail in a petrol powered car.

Stop/start driving will put more strain on the DMF, therefore it is 100% correct to say using a diesel for short distance journeys runs the risk of having to replace one.

And yes, of course a diesel can do big mileage without having either DPF or DMF trouble - my Dad's Avensis with nearly 190,000 miles is living proof of that, it's still on the original clutch, DMF and DPF. Thing is, that car is rarely driven around town (and let's face it, the Avensis is not known for giving DMF trouble anyway) so it's no surprise.