[Rudz]

I got 600 miles to the tank easy on my manual 320d, the old M47 lump which I quite preferred to the newer problematic N47 to be honest, 28mpg for a diesel is way to low? Sorry u seem to have investigated and fixed most of the problem areas, get the remap off and see if that improves anything ?

[Digitalize]

I get 550-650 miles from mine full to -10mls left. Most I've had is 51mpg out of it. Least was 38 haha

[Pumper]

Can't tell the actual number yet, but it looks like the new MAF made a huge improvement in MPG department.

At the moment I've done 81km and the hidden menu lists ~55 liter of diesel in the tank (6.01 menu says 20.8 35 55, the 6.02 menu says 54.2 and the fuel gauge is around the second mark).

So that is ~7.5l/100km or ~38MPG with 100% city driving.

Will have give the borrowed MAF back tomorrow and will fill the car up again. So I'll have accurate numbers tomorrow.

As for dashboard, it seems it is trolling me. Was showing 9.4l/100km when it was using ~11 and now it is showing 8.8l/100km, lol.

EDIT: arranged to buy the tested MAF for £95. Will save ~£30 (new one is ~£130) and won't have to change it again. Win-win. Won't be filling up tomorrow as a result.

[foey]

Just to add. I have a 2007 320D, 105k on the clock.

Throughout the Summer I can average 48.7mpg on the dash, after a number of resets. However, in the winter it does drink a little more. Mine is now showing 44.1mpg, but when very cold outside (~0-3c) I get around 39/40mpg on the dash.

Not 100% Accurate, but does give a indication.

[Pumper]

Dashboard just keeps on trolling me.

Went to Within Temptation concert on the March 4th. This was 260km trip in total (~240km of it highway). I have started with average fuel consumption of 8.8l/100km (32MPG - BS number) of the dash and came back with 12.6l/100km (22 MPG).

First figure was 100% city driving. Second after ~20km city + 240km highway at 115km/h speed with fairly constant ~44 MPG.

The spare key is showing 7.7l/100km (37 MPG).
The actual consumption is (387km with ~27l diesel) 7l/100km (40 MPG).

Is my BMW's ECU retarded of something? I get that there can be inaccuracies, but why did the average MPG go down after highway trip?

BTW, is the 44MPG figure at 70-75 mph good for automatic 320D with winter tyres? Was getting around 52-54MPG when doing ~50mph.

[Mr Rauf]

Originally Posted by Pumper

Hi everyone,

a couple months ago I bought a 2007 E91 320D (M47T2 engine) automatic and I can't get neither the advertised nor real reported MPG figures with my BMW.

Here's some info about the car:

- almost 217 000 km driven
- full service after purchase (engine/transmission oil, filter and the like)
- new battery
- replaced all of the glow plugs (was vibrating on cold start - new plugs fixed that)
- replaced both thermostats (used to get ~75C with old ones and now the temp stays at ~92C)
- remapped from 163 hp to ~190 hp
- tire pressure as the chart suggests

Before replacing thermostats if gave me ~22 MPG (13l/100km) driving around town. Now it gives me ~28 MPG (10l/100km).

Extra urban while riding at anything between 70-90 km/h (45-55 mph) at constant speed (sixth gear) the fuel consumption dial shows only 40-44 MPG (6.5-7l/100km).

So my question is: what else (apart from faulty thermostats) might be causing low MPG?

Hi mate

Regarding your glow plugs was your car shaking for a second or two at cold start which made you change the glow plugs?

[Pumper]

Can't remember any major shaking, but the engine start certainly was not as smooth as with new plugs. Changed them as diagnostic showed fault codes in 3 out of 4 of the glow plugs.

[jo5hm]

In regards to low MPG have you thought about tyres....

Crazy i know but i do the same journey each week and my mpg counter in the dash reads 50mpg went from some yokohama's to some vredesteins although alot more grippy i am now getting around the 43mpg

like wise i usto get 600+ miles to a tank now i can get around 580 if im lucky have to drive like miss daisy to achieve this where as the 600 was varied driving....

This is with a 57 plate e91 320d so m47 engine Mapped

When i noticed this change i also said to my friend who also had his tyre replaced on the front of his van just for some budget tyres as he was a little hard up at the time and he also noticed the drop in fuel economy on his van

[Aragorn30d]

Worth checking tyre pressures are right, but yes, tyres are rated for fuel economy, and some tyres are worse than others.

[Pumper]

Mine are two Goodyear Efficientgrip and two Micheling Energy Saver (205/55 R16). Both types rated B for economy and I get ~43-45 MPG when cruising at ~70-75 mph. PSI as listed - 2.1 front, 2.6 rear.

[vas210]

Your mpg should be above 30 , I had the same car and on short journey 100% city (london) never got bellow 35mpg.

[Pumper]

The low cruising MPG might be the reason for the overall low figures on my car. Not sure what might be wrong with it, thought.

Just drove parent's 2006 Volvo XC70 (heavy, AWD, auto, 136kw D5 engine) and was getting over 65mpg while driving at a steady 50mph, but never see anything above 50mpg in my 320D in the same conditions. Average with mostly city driving is less than 28-27mpg on the Volvo, while the BMW is 35-34mpg.

[Jase 320d]

Better weather over the last 300miles i've got 48.7mpg combined

Not bad

[Pumper]

Hey guys, reviving this thread again.

Looking for any opinions on what might cause low extra-urban MPG. City seems to be ok, at least as far as I can tell (too many variables to be sure really), but it is obvious that the car is drinking too much while driving at a constant speed (be it 60, 70 or 80 mph).

What I get:
40 or less at 80-85 mph
44 or less at 70-75 mph
47 or less at 60-65 mph
50 or less at 45-50 mph

So even if I do most of the mileage on the highways, I end up with 40 MPG (best I've seen in the summer, ~70% highways at ~70mph) or less.

More about the car:
- 2007 e91 320d 120kw, automatic
- new engine oil (castrol 0w40), transmission oil, diff oil
- replaced all of the filters
- all 4 new glow plugs
- new thermostats
- new MAF
- fixed leak in the intercooler
- new front brake disks/pads
- 16" 205/55 no-rft summer, rft winter at 2.1 bar front, 2.6 rear

Any thoughts?

p.s. can hear a droning nose from the rear when driving at 65-75mph (no sound at lower/higher speeds).

[Jase 320d]

Droning noise sounds possible wheel bearing or less likely a sticking caliper

Either will reduce mpg

[OGM2LCI]

I had an old M47 in E46 guise...got 38-39 combined driving, not heavy footed either..

Unplug the MAF and the engine will revert to a 'default' setting that may improve running and MPG, if it improves with the MAF unplugged then you may need a new one, MAF's can also fail without throwing a code on those engines

I'm not sure it'll have a DPF either

Does it black smoke heavily when you floor it? You may have a leaky injector as they are also known to get a little weak after a set amount of miles

Either way I hope I may have helped a little and hope you get it sorted

[Jase 320d]

No m47 engine has a dpf UNLESS specced from the factory. It was an option but i havent seen one

If it has a downturned tailpipe it has no dpf

[Pumper]

Originally Posted by Jase 320d

Droning noise sounds possible wheel bearing or less likely a sticking caliper

Either will reduce mpg

But can it be either of the two if the noise is there only at specific speed?

Had a bad wheel bearing on a Mazda and it used to drone at any speed, just used to get louder when going faster.

Originally Posted by James-B93

I had an old M47 in E46 guise...got 38-39 combined driving, not heavy footed either..

Unplug the MAF and the engine will revert to a 'default' setting that may improve running and MPG, if it improves with the MAF unplugged then you may need a new one, MAF's can also fail without throwing a code on those engines

I'm not sure it'll have a DPF either

Does it black smoke heavily when you floor it? You may have a leaky injector as they are also known to get a little weak after a set amount of miles

Either way I hope I may have helped a little and hope you get it sorted

MAF is new (old one was dead and did not show any codes).
Car is with DPF, but it seems to be fine - no codes, no limp mode.
Never get any smoke.

[CraigUK]

I had an e91 320d auto with the m47 engine for 6 years and my average mpg was iro 41 to 43 mpg. Could manage around 49 to 50 mpg on the motorway.

Have an f11 520d at the moment with the n47 engine and my long term average is 49.5mpg with mixed driving. Managed 70mpg on one run to work.

To summarise, there's a big leap in fuel economy between m47 an n47. I think that the older 6 speed auto is also no where near as good as the new 8 speed for economy.

[Pumper]

So, here we go again.

Filled up after two highway trips - total of 573km (360 miles) driven, average speed of ~60mph (was holding at ~70mph on the highway). Filled up 40,25 liters of diesel, which gives me 7,03l/100km or ~40,2 MPG. Pretty sure this can be considered to be crap economy.

What I've noticed is that every single time while stopping the car, my instant consumption needle shoots to around 15l/100km (arprox. 19 MPG) at the moment then the box shifts down to the first gear. Is this normal on these cars or is this a symptom of a specific fuel economy related issue?

Car get's to 88-89C (higher during DPF regen), MAF replaced two years ago, oxygen sensor last month. Air filter is clean, fuel filter replaced last winter after diesel in my car froze. Checked the wheels after the trip - none where hot, so can't be sticking calipers. 205/55R16 tyres at ~31psi front, ~38 rear (as stated on the sticker).

[vladmury]

Regarding fuel consumption needle, thats normal to all e90/e91.

[John320d]

I have noticed that you are in Lithuania, have you compared mpgs with other local cars. Just wondering about the fuel that's all.