DPF Economy

[SteveBray]

I previously had a 2004 1.9 CDTi 16v Vectra and typically got almost 48 MPG with my usual driving and while touring Scotland got a little over 54 MPG, these are genuine figures and not the fuel computers idea.

I now have a 2006 1.9 CDTi 16v Signum and typically get 43 MPG and 48 MPG at best if driven very carefully, quite a difference which I can only assume is due to the DPF?

Any one else found the same results, is this normal, does the DPF reduce economy and sap power?

[Big Sig]

it only uses fuel when on a regen cycle. As far as I know, it shouldn't sap power or otherwise reduce the mpg.

[Signum_CDTI]

However, when it is on the regen cycle.... which with mine is about every 2k, it drinks the fuel like a 3.2 V6, I kid you not!

[Kcs]

I traded in my 56 plate 150 cdti hatch for a 07 150 cdti estate xp, used
to get 48 mpg combined, but now only getting 40.5 ! im not very
impressed at mo ! the book states it should get around the same as
the hatch, even with the 19" wheels !

[Signum_CDTI]

What sort of mileage are you doing in it - and is it mainly motorway or city driving?

[DenisCB]

I average 45 mpg from my Signum with a lot of mixed mileage, including a fair thrashing on the motorways. Looking at the way mpg falls away with higher speed, I suspect this thing has the aerodynamics of a brick. I was on the M11 last week, and in traffic could only do a fairly steady 60 mph. At that speed, mpg was 52-53. But at 82-85mph, it drops to around 42 mph. I never noticed anything like that sort of variability with my previous petrol Vectra B, which I suspect was a lot more slippy through the air.

[Kcs]

What sort of mileage are you doing in it - and is it mainly motorway or city driving?

I do a mixed type of driving, cover about 380 miles a week !

[Signum_CDTI]

If it is like mine and regens every 1500 to 2k miles, then you will notice a drop in economy from car to car - have you done the airbox mod and ghanged to K&N filter??

After doing this, at 70 ish mph i was averaging 52 ish mpg!!

[Kcs]

If it is like mine and regens every 1500 to 2k miles, then you will notice a drop in economy from car to car - have you done the airbox mod and ghanged to K&N filter??

After doing this, at 70 ish mph i was averaging 52 ish mpg!!

Yep done the air box mod and K&N, i have noticed that it runs
rough at about 2k from time to time, not sure what it is, because
some days it runs so sweet !

[Signum_CDTI]

hmmmmm.....
Mine is averaging around 47 ish to the gallon at the moment, before it was struggling to reach 44.
My average weekly mileage is not too dissimilar to yours, consisting of motorways (M53) and city commutes (to work) and I have noticed a difference since the mods....