Very poor mpg at 21.5 mpg

[v50inred]

My old NHS Trust bought 350 Zafira cdti's with Autobox for RRV's.

I never saw one that was showing more than 18mpg on the fuel computer.

DPF's and urban usage don't go together, autobox will make things worse.

Though they also had some XC70's (11 plate) bought by the Government and they did low 30's in very similar usage.

[Zeb246]

Well...Not really cause my BMW 535D get's 35mpg on the motorway, and 28mpg on city and thats an auto, with dpf removed, and cleaned injectors.

So how come my S40 D5 is getting **** mpg?

[v50inred]

Not sure what you mean.

Do you think 28mpg is good or bad?

The 535d is not known for being economical. If you were getting those figures from a 520d I could see why you would by concerned.

It is a well known fact that a DPF and particularly a DPF with an autobox doing mostly urban use is not good recipe for good economy or the health of the DPF.

The Zafira cdti with an autobox was one of the first vehicles to come with a DPF, from 55plate onwards.
So it is not surprising that it also proved to be a bit of a pig.

Incomplete regens, diesel in the sump leading to turbo failure, top end failure, bottom end failure and the oil turning into a thick Vaseline type substance, calling it sludge doesn't do it justice.

[Zeb246]

For a 535d done 127K miles getting 28-30 mpg in the city is good enough, my S40 sometimes struggles to get 25 mpg in the city, and even worse on the motorway. DPF removal does make a difference, it's much smoother, quicker, increases mpg, no soot or carbon is in the system, which means it won't clog up your turbo, you won't get the limp mode problems, and good on fuel economy.

Don't know why people think removing dpf/catalytic convertor harms the "environment" clearly doesn't. I don't believe that crap anyway IMO.

[v50inred]

DPF's are a flawed technology indeed.

Take the Nissan Pathfinder as an example.

Euro 3 auto will give you 30mpg overall, in same usage a Euro 4 auto with a DPF will give 22mpg.

How that can save the planets resources I don't know.

Makes sense in Brussels though.

[Bendolfc]

You bought a low milage car. Engines that are barely used and never stretched bed in differently to engines that are pushed harder from the start.

Yours might loosen up and improve over time, or it may end up being a pig all its live.

[Zeb246]

I regret to buy a low mileage car ever again in the future. I wish I'd bought a high mileage S40, would've gave me less trouble and hassle

I am willing to keep the car until I hit 60K, then sell it. For now I will have to live with the ridiculous mpg. I might change the oil, oil filter, fuel filter and clean the EGR Valve, then see if it makes any difference in mpg.

[RSVolvo]

Why wait if you bought the car at 43,000, then 60,000 is 17,000 miles away. If you are only getting 21.5mpg and could be getting 45mpg (more typical for a D5 - or other more modern performance diesel) then at current prices it's going to cost you nearly £3,000 extra in fuel. That's a long way towards a newer car...

[SonyVaio]

Originally Posted by Zeb246

I regret to buy a low mileage car ever again in the future. I wish I'd bought a high mileage S40, would've gave me less trouble and hassle

I am willing to keep the car until I hit 60K, then sell it. For now I will have to live with the ridiculous mpg. I might change the oil, oil filter, fuel filter and clean the EGR Valve, then see if it makes any difference in mpg.

Well Zeb a good service and a clean out is always the best places to start. What sort of air filter have you got? If you've got a performance filter and especially an oil based one (K&N) then you will probably find that there has been a little too much oil on it and coated your MAF. This in turn provides false readings and can return poor MPG. Even if you've not got a K&N type filter a clean of the MAF is also a good idea anyway when trying to tackle an abnormally low MPG.

So on the service side of things to try improve your MPG you should check/clean/replace the following:

• Fuel Filter
• Oil Filter
• Oil
• Air Filter (replace, unless K&N type then clean correctly)
• MAF
• EGR (plus associated pipes that can be reached)
• Tyre pressures (set to eco settings (as if car was fully loaded settings)
• Check all brake callipers for drag
• Wheel alignment (scrubbing or crabbing has an effect on MPG)
• Actual Tyres (Check online and see what efficiency rating they have, you may have G rated tyres?? - won't help)

Are you going off computer only or are you measuring economy on calculation of fuel used against mileage driven (pump to pump fills)?

[Zeb246]

I got a list of things to do from SonyVaio thanks Helps a lot...
I haven't fitted any after market filter, I assume it's just the standard air filter. Tbh I haven't checked since I bought the car. Will have a look at it tomorrow and check out the maf. The oil does look a bit too black and runny, even though the previous owner serviced the car from a specialist, and has been stamped in the service book.

I'm relying on the trip computer, i'm not good with calculations lol.

The only reason stops me from selling the S40, is all the gadgets came with the car. I know for a fact, I won't find another car with all the gadgets like this S40.