Quick tap at the Casio suggests that the difference in cost for 5000 miles is £43 a year @ £1.50 a litre.

How much does insurance, MOT, tyres, servicing etc add up to each year?

£43 is not a big cost, about what special fried for 2 three times costs at our local take away.

But you say the difference started in January, that is when you are buying "winter diesel" which always gives a few less mpg.

Are you carrying out the exact same journes now as before?

One more question, are you filling at the same garage each time?

Edited by skidpan on 06/07/2024 at 15:29

With regards to the DPF. When its attempting a regen your mpg will plummet but not by 4 to 8 mpg, on our Ceed it would drop form the usual 50 mpg to about 30 mpg but only for about 20 minutes. But if its trying to carry out a regen and for some reason the car is saying NO that could be your issue.

Read your handbook regarding a regen. Loads of people insist that driving at high revs does the job but that is not true. All it does is waste diesel and create more soot. On the 3 diesels we have owned in the past with DPF's the advice was drive between 1600 and 2000 rpm for about 20 minutes. Too many revs is too much gas flow through the DPF to allow it to heat up to the 600 degrees required.

5000 miles a year is danger territory for a diesel with a dpf, you would be better off with a modern small petrol turbo. Our Fabia 1.0 TSi 110PS averaged about 50 mpg over the 6 years we owned it with no dpf to worry about. Remembering that a replacement "quality" dpf costs over £1000 by the time its fitted any savings you make would soon be lost many times over.

We sold our last diesel when the wife retired, her annual mileage dropped from about 15,000 to 5000 which in a 5 year old car was a ticking time bomb. It helped that she wanted to change anyway.

Also have u changed the air filter If its sooty change it as that results in poor economy.

Either change it every year or 2 regarding condition of the filter.

Shouldn't be any soot in your air filter unless you drive a lot in very strange atmospheres :-)

KIA Pride EGR used to feed into the 'dirty' side of the air filter box. That filter could certainly look 'sooty'. Don't know if any others did this.

Shouldn't be any soot in your air filter unless you drive a lot in very strange atmospheres :-)

KIA Pride EGR used to feed into the 'dirty' side of the air filter box. That filter could certainly look 'sooty'. Don't know if any others did this.

Yes, I had overlooked that possibility - if dirty (diesel) gas is recirc'd it would make sense to pipe it through the filter, I suppose. I wonder if the filter renewal/check interval has allowed for that ?

Kia Pride was petrol.

I would be wondering what a service could have done to make the MPG worse. If it didn't include a fuel filter that was due a change, it wasn't a very thorough one.

I wonder if they put the right viscosity oil in (or if it was too thin before)?

Most of us can only dream of 50mpg!

Both my Peugeots (one petrol, one diesel) give me comfortably more than 50mpg, John - but that is because of the kind of journeys they do.