Question of the day:

I live in Prague but want to buy my Octavia in Germany. Both countries offer the option of DPF on diesel motors. I understand this reduces pollution (diesel partical filter) and the EU may require these on new cars soon. But if they are not required now, what is the reason for paying an extra 1000 euros for it now.

To help the environment? Or to insure against restrictions tightening later?

Anyone know the arguments for whether or not to invest in this?

Unless your law requires this filter system to be fitted now then why spend your hard earned cash on this item unless you are Green Freak.

no argument for paying extra as far as I can see. Just something else to fail.

no argument for paying extra as far as I can see. Just something else to fail.

and they cost money at service time to have some liquid added to make the thing work

No maintenance required for particulate filter only on systems with particle filter

with additive, it is necessary to replace the additive every 4 years or every 120,000 kms or when a warning to do so is shown on the instrument panel. This will only occur when les than 0.3 litres remains in the additive reservoir.

With my current Euro III engine, some of the carbon goes out the back as Carbon Dioxide, and some as soot.

With a Euro IV engine fitted with a particulate filter, less Carbon Dioxide is produced until the accumulated carbon is removed from the filter. Then it all gets converted to Carbon Dioxide, leaving no soot.

So from a given quantity of diesel, a car with a particulate filter produces loads of carbon dioxide, and one without it produces some soot instead of some of the carbon dioxide.

Now I thought we were trying to cut down on carbon dioxide emissions ...

ALL diesel-engined cars sold in the EU must now meet Euro IV emission standards, which limit the amount of ultra-fine particulates emitted from the exhaust system. Ultra-fine particulates are linked with asthma and various other respiratory illnesses.

To reduced particulates, vehicle manufacturers use a filter in the exhaust stream. Any filter will gradually get blocked and so a mechanism is needed for cleaning the filter. There are two technologies for doing this: a platinum catalyst and a fuel additive. The technologies using an additive are generally superior as they are suited to all usage patterns (motorway driving and stop-start/short journeys) and also, they reduce other harmful emissions such as NOx.

VAG have mostly adopted the fuel additive route, as have Renault and Peugeot (Peugeot diesel engines are widely used by other vehicle manufacturers).

The original fill of additive (5 litres?) is designed to last over 100,000km - but when it does need refilling, it is a costly refill. I don't know the dealer price, but the additive manufacturer charges VW around €20/litre.

One final note. The active component of the fuel additive is sold in other markets as a combustion improver. In other words, it makes the fuel burn better, to give better performance and/or lower economy.

VAG have mostly adopted the fuel additive route' date=' as have Renault and Peugeot (Peugeot diesel engines are widely used by other vehicle manufacturers).

[/quote']Unfortunately, this suggests that Skoda are only using additive-type filters on the Superb. Newer cars (Octavia and Roomster, and by implication the next Fabia) will use a catalyst type.

I'm wondering whether I need(ed?) this type of filter. I am actively looking into something like this, mainly to reduce the amount of soot under Jason-like planting of the right-foot

Personally I'm after something that reduces the soot output more than the CO2 output, as the soot is the main reason for the Furby getting VERY dirty VERY quickly at the back, especially post-remap/LPG

How about two-foot long extensions to the exhausts to get the soot clear of the car?

"ALL diesel-engined cars sold in the EU must now meet Euro IV emission standards, which limit the amount of ultra-fine particulates emitted from the exhaust system. "

If this is true, why is the DPF system still an (expensive) option when buying a new Octavia?

"ALL diesel-engined cars sold in the EU must now meet Euro IV emission standards' date=' which limit the amount of ultra-fine particulates emitted from the exhaust system. "[/b']

If this is true, why is the DPF system still an (expensive) option when buying a new Octavia?

It isn't an option on uk OctyII's as far as I know, it's standard and is required to meet Euro IV standards. Same applies to the 2.0 TDI Golf V. The 1.9 Golf TDI particulate emissions are actually just below the maximum limit so currently it doesn't require a particulate filter.

VAG tech.specs.for the Passat indicate that versions of both the 1.9 and 2.0 (140) TDIs with DPF are produced but that the 2.0 (170) TDI is only produced with a DPF. In the UK, AFAIK, the Passat is only offered without a DPF on the 1.9 and 2.0 (140) TDIs.

It makes sense not to fit a DPF to vehicles capable of meeting EU4 regulations without one. Some countries may demand a DPF as a matter of course others may operate regulations more stringent than EU4.

Ah -- was wondering why DPF is an option on the 2.0 TDI in Germany and Czech Republic (where I am shopping).