I think I'd be going for a petrol in that case. Have a look on Parkers site and use their tool to work out whether it's economical to bother with diesel; you can put in lots of different car models and compare them as well.

There are two main kinds of DPF I know of. Additive based, and the other kind.

It's telling that the additive type ones need a warning light which actually tells you to go on a drive to regenerate it - there's no light for my type of DPF. People seem to have a lot of trouble with the additve based DPFs, often found on French engines.

Also there's no strict guidance from Ford on how to drive to enable the DPF to regenerate - it seems to take care of itself whatever the driving style.

Edited by ddr on 04/07/2011 at 17:20

Had a 2008 Mondeo 2.0 TDCI manual for over 3 years and 36,000 miles. This has a coated DPF (no liquid additive).

Around 60 - 70% of my driving is journeys of less than 10 miles, and my daily commute is 4 miles each way in traffic.

I had no DPF problems. Ford seems to have built a mileage-based failsafe routine into the ECU which causes a regen every 500 miles or so, from my observations.

However I did keep the revs above 1,750 (using 3rd gear in 30 limits, I don't like to lug the engine at low rpm in high gears anyway) to keep exhaust gas temps high.

The one sure sign of a regeneration is the engine cooling fan coming on. You can hear this, and the exhaust note does change a little, becoming more 'boomy'. If you're near your destination and you hear this, it's worth driving round the block until the fan cuts out to complete the regeneration, in my view.

I am thinking of buying a diesel car. I drive mainly urban for about 40 min, the max. speed is 30mph and the distance 10 miles (one way). With this particular type of daily commute will I have trouble with the DPF?

I dont think you sound like a diesel car candidate. I have an Audi A4 TDI with DPF and do on average 2 motorway journeys of over 150 miles each week. In between my wife uses the car and so far in 4 months I have seen my car do 1 DPF regeneration after 7 days of only round town driving. In your case I think you would see a lot of regen's and this would also affect the fuel consumption.

In the case of Eolys or Ad-Blu systems, as someone else has said it costs money to fill the tank but otherwise its okay. After all these fluids are based on wee wee as I understand it !

The general moral is dont buy a diesel unless you intend to work it hard.