Why isn't it recommended to get a diesel...

They're noisy, dull and attempts to make the less noisy and dull have made them less reliable.

DPF, injectors, DMF problems all seem more common on modern diesels.
 
Diesels do get a bad press on here but it's for a select number of valid reasons.

Very few people would argure with a diesel rep mobile if you are hammering 20-30,000 miles a year down the motoroway. In fact, the economy saving's make very good sense. It's the new breed of eco city hatchbacks that cause the issue. One of the biggest problems with todays modern diesels is the regeneration cycles needed for diesel particulate filters. These often need a good solid run (i believe around 30 minutes) above 60 mph, in order to clean the DPF. Of course motorway cruisers get these reguarely getting rid of a lot of the worries.

The issue comes with small city diesels is that generally they never get these long runs. Afterall, if you were doing long runs all the time, why would you want a small city car? These never get the opportunity to run a DPF regneration cycle causing problems very quickly. They do tend to be less refined than their petrol counterparts, and in stop start city driving don't really offer any economy savings. Even the small amount they do is offset by the fact the diesel's generally cost more to buy.

In short, diesel is good for people who do a lot of miles a year, the technology really does offer savings. It is however very bad for people doing short city runs who are suckered in by the fact the book says "65mpg" instead of the "45" it's equivalent petrol would get.
 
How many people have had problems with DPF filters on here, out of interest? I do wonder about the true scale of the issue. I asked around the office and could only find one person that had suffered a fault with a DPF in their car - but it was caused by a fuelling problem rather than numerous short trips.

Just curious :)
 
"hai. i want to say £60 a year on cheaper tax. 42mpg vs 32mpg sounds like a winner too. i know, im going to go out and spend £xxxx to save £xxx per year
 
Lashout_UK said:
How many people have had problems with DPF filters on here, out of interest? I do wonder about the true scale of the issue. I asked around the office and could only find one person that had suffered a fault with a DPF in their car - but it was caused by a fuelling problem rather than numerous short trips.

Just curious :)
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You should look on some of the vag forums. I have a PD engined VAG 1.9tdi and looked into changing it recently for a newer CR engine with a DPF. It's not just problems with clogging it problems with fuel economy. There is a thread on skoda forums where people with the 1.6CR 100bhp are getting 45-48 MPG on motorway mileage. Some are having to do sub 60 mph on a run to get over 50mpg. I got over 57mpg when mine was new and on 45k now get 65mpg to work.

The DPF is killing the MPG, some are having the car revs rocket while sitting in traffic while the DPF tries to do an emergency regen. You could get away with town mileage with a diesel, my wife did until I took over ownership of the car. You can not even consider using one round town anymore.

My work stupidly bought VW caddy vans for use on the airport, driving from stand to stand when needed. Bearing in mind the speed limit a max of between 15mph and 20mph I had a van with less than 280 miles try to emergency regen itself to the point I had to get out the van because I thought it was on fire. When I got back into the office a collegue and poster on here had the same happen that night. These won't be a good buy in 3 years :D

I fail to see how the DPF has been good for the environment if more fuwl is needed to get the same economy as a non DPF car.

My friend has a reader and he runs a 207 on the same route as me with a CR engine, his DPF was 18% loaded using motorway mileage. He regularly has people round so he can do a regen for them.
 
Lashout_UK said:
How many people have had problems with DPF filters on here, out of interest? I do wonder about the true scale of the issue. I asked around the office and could only find one person that had suffered a fault with a DPF in their car - but it was caused by a fuelling problem rather than numerous short trips.

Just curious :)
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I had a 1.9 Diesel Megane. I very rarely did any motorway miles with most of my driving being around town. I only purchased a diesel as it was pretty much the quickest car I could get whilst being very cheap to insure.

Anyway, the poxy DPF filter was constantly regenerating as I rarely drove above 60. This drove me mad so I sold it
 
You can have the DPF removed or the filter gutted and refitted and then have the fault mapped out. Bit of a pain to pay more on top of the price for the car but it can be done. I have removed the EGR and DPF from my A4. It's not that great on fuel either compared to the old 1.9 engine - don't know if that is just a VAG thing.
 
Lashout_UK said:
How many people have had problems with DPF filters on here, out of interest? I do wonder about the true scale of the issue. I asked around the office and could only find one person that had suffered a fault with a DPF in their car - but it was caused by a fuelling problem rather than numerous short trips.

Just curious :)
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It's a very real problem, every time I go in the garage they have a car in with DPF failure, it's become bread and butter work for them now. Often it causes secondary engine problems too. Last time they were battling with a 1 series which idled like a dog after DPF replacement, think it ended up being something to do with PCV and that was another £250 part.
 
I was very close to having the DPF removed completely and a remap, but that was going to cost about £500. So i sold it and bought a Civic Type R instead
 
Here is a very good post on DPF's on VAGs and why I'd avoid one like the plague unless I did long motorway runs every time I drove.

Even in motorway mileage you want to have a long enough run constant to get the regen done, approx 10 mins in the required window. Otherwise for the fuel burn in aborted regens you may as well just get petrol, which I think I will do once my PD non DPF requires replacement.


http://www.seatcupra.net/forums/showpost.php?p=2901351&postcount=1
 
1. Purchase price is usually much higher, meaning a payback period of 7 years or so at 10k per year.

2. Faults with DPFs and dual mass flywheels are very expensive to fix. Petrols don't have these parts.

3. Petrol is just nicer in terms of refinement, although modern diesels may actually be more fun to drive because the power is more usable (max torque can be at 1500rpm rather than 4500rpm for a normally-aspirated petrol).

If you're buying secondhand it's less clear-cut, and if you see a diesel pre-dating DPFs and DMFs (pre-2007 ish) which is a good price, go for it.
 
rogerzilla said:
2. Faults with DPFs and dual mass flywheels are very expensive to fix. Petrols don't have these parts.
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Virtually all cars have a DMF these days. Including the petrols.

The petrol ones are less prone to failure, however, due to reduced torque and vibration. They're incredibly prevelant but you don't hear as much about them because they don't tend to go wrong too often.

For example, every Mercedes-Benz 190E petrol has had a dual-mass flywheel fitted, and they started building those in 1982. Every E46 petrol, including the 318i, has a dual-mass flywheel too - and so on.
 
A quick addition; on another forum someone made the very valid point that diesel has had a free ride in terms of emissions for many years. Petrols have been very clean since 1992 when 3-way catalysts became mandatory. Diesels continued to spew PM10 particulates as well as visible soot and huge levels of nitrogen oxides, which is why London sky is brown in summer. DPFs, EGR and other tricks are to try and clean up the filthy diesel exhaust. Dual mass flywheels (basically a flywheel with a rubber connection between the hub and the outer part) are to try and reduce the vibration from diesel knock (or, as you say, a petrol engine, although they're not really necessary) and are nothing to do with emissions.
 
I can see why people buy diesel cars if they're doing a lot of mileage.

It's when people start buying diesel convertibles and are willing to get rid of their car and buy a diesel to get that extra 10-15 MPG, even though they drive less than 20 miles a day.
 
flibbage0 said:
It's when people start buying diesel convertibles and are willing to get rid of their car and buy a diesel to get that extra 10-15 MPG, even though they drive less than 20 miles a day.
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Whats wrong with people buying diesel convertibles, if that is what they want? Car manufacturers build them because there is a demand.

I have a diesel and it's very good to drive and handles well. It obviously doesn't sound as good as a petrol and I don't kid myself that it's the best engine out there. It does however have good performance and is very good on fuel, which is what I want.
 
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