Poor Fuel Consumption 03 406 s 2.0 90bhp Diesel

[MichealKnight]

Hello,

In the last year I replaced my 406 rapier (petrol) with an 03 406 Diesel Estate(now done 116 000 miles) in great condition. I am interested to find what fuel consumption I could expect. I am a conservative driver...but am only getting 44-45 mpg. I expected a better mpg return. There is no smoke...good tyres, no binding, normal acceleration. Can anyone shed any light on why mpg is quite low. A friend has an X reg saloon executive (with a heavy foot) and gets 51 plus (late 40's) winter no problem.

If anyone has any thoughts please let me know.

Thanks,

Jon.

[Doggy]

Hi Jon & welcome to the forum.

There are many possible reasons - you've clearly considered some of the obvious ones.
Your friend's saloon will be lighter than your estate, also an 'X' reg, executive means it must be a 110 HDi.
The 110 has an intercooler, (which the 90 lacks), giving greater efficiency.
The 110 also has taller gearing.
These factors may explain the difference, (if you check the 'official' fuel consumption figures they will confirm better mpg from a 110, which is reflected in the emissions and hence the road tax band). However, I think the difference on the combined cycle is only about 2 mpg.

Are you confident it's been correctly serviced in the recent past? If not an oil change / fuel & air filters may work wonders. Also worth checking you have no leaks in the pipe work between turbo & inlet manifold - even a very slight leak will upset the fuel injection calculations.

[lozz]

44-45 mpg. thats about normal, id say,
if its a 110, a remap increases mpg alittle, ifound with mine,

ithink 44mpg is brilliant, drive apetrol car for a bit and go back to a deisel it makes you realise how good they are,
thats just my opinion, im sure everyone elses will differ,

[rwb]

Is that measured by the trip computer or by brim-to-brim filling?
I get a discrepancy of about 10mpg to 12mpg between the two; computer says 48 when brim-to-brim comes out at 60. However, I seem to be unusual in having such a massive discrepancy.
(More discussion: Is the trip computer honest MPG wise?)

[Blubayou]

My HDi 90 averages 52mpg in reality (tank to tank) and the computer reflects this fairly accurately (50mpg in this case).

If I thrash it round town or lots of short journeys 42mpg is quite typical, on the long motorway runs I usually get around 55mpg taking it easy & sitting with the trucks.

Pretty damn good for a big old estate!

[MichealKnight]

Hello,

Thanks for all your input and apologies for a delayed reply (I've been away for a few days).
I will take all you input into account and try to figure out what the problem is!

Thanks again,

Jonathan.