d5 mpg

[Lexington013]

Not had mine long, but averaging 33.6mpg over a mix of driving, mostly A roads and motorway though.
Mine is a manual so would expect mid 30s.

[Tannaton]

They're not very good at economy but a 2.2 ton 4WD brick was never going to be... Driving styles clearly impact the economy and the on-board computer is a guide only, but yo don't seem to be getting what you might do.

Suggest you check if the intercooler is leaking - especially of the car seems down on power. Oily film at the bottom of the radiator is a tell tale sign - there's lots of articles on here about it.

[dylan5084]

My trip computer tells me iI'm averaging 30 mpg, but I've calculated it over the last 3 brim to brim tanks and it's defo 23 at the most, I am calculating it to imperial gallons, which is 4.546 litres, makes each fill about 15 gallons last fill was 68 litres. I keep my tyres at about 40psi, I think it's probably my driving style that affects it most, the car has completely warmed up by the time I'm at work too... I'll check my wheels to see if Any are getting hotter than the others, I was just shocked that the trip computer would be so far out....

[Chesney46]

My 2003 D5 is currently returing 25 mpg with a split intercooler. We travelled from Kent to Devon a couple of times last year and got it to 32. I think the intercooler was on it's out then too.

[owenfackrell]

My 54 plate manual does over 400 miles per tank with the trip showing 37+ long runs getting higher with 45+ seen on one run. It's not often it does a trip less than 16 miles which helps. My commute is made up of empty 40mph roads lasting around 10 miles before I hit town and traffic with this reversed the other way.
I tend to keep the revs under 2000 and use 5th and 6th as much as possible. I find that keeping an eye on the miles per tank is a good way of keeping an eye on the consumption.

[A lex]

Im averaging just under 28mpg from new.

2010 D5 with Polestar.

If coaxed itll do 35mpg+

But I drive it like I stole it, mostly on the motorway at 80-90mph.

For a heavy, AWD car, that doesnt seem too bad.

OP: For lots of short journeys the MPG doesnt seem outrageously low, although I would perform some rudimentary checks on the intercooler.

[dylan5084]

It doesn't seem down on power, but I'll give the intercooler a check, what should I be looking for?

[A lex]

Oil....

[cheshired5]

Originally Posted by dylan5084

It doesn't seem down on power, but I'll give the intercooler a check, what should I be looking for?

Also, if your intercooler is blown and no longer efficiently cooling the turbo and exhaust gasses, your intake air temp (IAT) will be high and likely your manifold absolute pressure (MAP) low.
Both sets of figures are available using diagnostics costing as little as £5.

[Tannaton]

Originally Posted by dylan5084

It doesn't seem down on power, but I'll give the intercooler a check, what should I be looking for?

If you remove the lower skid plate from the subframe (6 x 14mm bolts from memory) this will expose the bottom of the radiator etc. If there is an oily film on any part of the bottom of the rad then chances are the intercooler is leaking.

The effect of this is that not all of the air that is being pumped by the turbo is getting into the engine - but as the leak is downstream of the airflow meter the ECU will be calculating the amount of diesel to inject based on both the air getting into the cylinders and the air that has leaked - i.e. it's over fuelling. As a result there will be insufficient oxygen in the cylinders to burn the amount of diesel being injected.