[Pearler]

Just refilled and worked out I have been getting av 33mpg from my 325d E92 2009 M Sport.

I've not been driving it like it's stolen either, I've actually been trying to get reasonable mpg. It's got 46K on the clock, not a high miler. Just had all the glow plugs changed, as one of them was out. Had the theromostat changed as well as it wasn't getting up to temperature, which it is now.

Any thoughts? Something technical malfunctioning perhaps? I'd be happy with 38-40mpg, but 33mpg is way too low given I've been taking it real easy.

[Wobble]

It could just be with the colder weather we're having x

[OGM2LCI]

I take my 320d really easy the majority of the time and average 38...

What sort of driving are you doing? Mainly motorway miles or town driving?

All down to what environment you're driving in, it might be all clear and open roads but it might be very hilly, all dependant on so many different things

[djgandy]

Originally Posted by Pearler

Just refilled and worked out I have been getting av 33mpg from my 325d E92 2009 M Sport.

I've not been driving it like it's stolen either, I've actually been trying to get reasonable mpg. It's got 46K on the clock, not a high miler. Just had all the glow plugs changed, as one of them was out. Had the theromostat changed as well as it wasn't getting up to temperature, which it is now.

Any thoughts? Something technical malfunctioning perhaps? I'd be happy with 38-40mpg, but 33mpg is way too low given I've been taking it real easy.

Depends on your driving type, diesels are poor on short journeys and take a long time to warm up. 33mpg is still very poor though considering I'm hitting 30mpg from a 335i.

Diesel experts will chime in i'm sure but IIRC faulty thermostats can cause this kind of issue.

[Aragorn30d]

if its a short commute (say <5 miles) especially if town driving or lots of speed changes/roundabouts/junctions etc, then thats probably about right tbh.

Mine usually averages about 40 over a tank and my normal commute is about 40miles each way of motorway, though sometimes a bit congested etc.

But the wife used it for a few days a week over the last tank and the average dropped to 37. That was with me still doing 160miles of motorway a week, and her doing maybe 8-10miles a day total of town driving. Which shows you just how much of an effect short trips has.

However, its worth checking for fault codes, and doing a live data check to ensure the engine is actaully warming up properly. Most of these cars have faulty thermostats at this stage of their life if they havent been replaced already.

[Pearler]

Thanks for the posts.

the thermostat was found to be faulty a couple of weeks ago and both the EGR and coolant stats were changed, the engine is running up at 90degs C now which is good. So I was expecting an improvement. No other faults stored or shown on the ECU when it was in the garage.

I have 9miles to the office 3 times a week on 60mpg roads but normally can't get over 50 as there are a lot of Honda Jazzs in the area. I have to travel to another building 3 times a week which is about 24 miles is dual carriage way, cruising at 80-85 mph.

Was expecting better out of it but if this is the way it's gonna be I'll suck it up, like my fuel pump.

[Aragorn30d]

Doesnt sound too bad a run then, so yeh i agree you should be getting a bit more.

Did the garage use the proper BMW equipment, or a generic scanner. My generic scanner ignores quite a few faults that the proper BMW stuff doesnt.

[Pearler]

Originally Posted by Aragorn30d

Doesnt sound too bad a run then, so yeh i agree you should be getting a bit more.

Did the garage use the proper BMW equipment, or a generic scanner. My generic scanner ignores quite a few faults that the proper BMW stuff doesnt.

It's an established independant BMW specialist run by ex BMW senior technicians. I rate them well, very thorough. I expect they use good equipment, the establishment is pretty professional.

It is going in Monday for a dash board rattle I can't cure, so I'll talk to them about the MPG as well I reckon.

[OGM2LCI]

How does the figure on your computer compare with the one you have worked out?

Are you getting any smoke on start up or any excessive smoke if you put your foot down?

Not sure if leaking injectors would bring up fault codes or not but could well decrease your mpg, also check other little things like the breather pipe on the fuel tank, if that has broken it may leak, maybe not enough to bring your mpg down to that but worth a check

[Pearler]

Originally Posted by James-B93

How does the figure on your computer compare with the one you have worked out?

Are you getting any smoke on start up or any excessive smoke if you put your foot down?

Not sure if leaking injectors would bring up fault codes or not but could well decrease your mpg, also check other little things like the breather pipe on the fuel tank, if that has broken it may leak, maybe not enough to bring your mpg down to that but worth a check

Good question, the MPG on the computor says average of 39mpg, but it definately is telling lies. Is that common?
No smoke on start up. I've had a look out the back at night as well to see if there is much smoke in car headlights with quick aceleration, literally no smoke at all. Seems to run cleanly.

I'll check the breather pipe, cheers James.

[Aragorn30d]

i find my computer pretty accurate so long as you reset it after each tankfull.

[apollo]

Originally Posted by Pearler

Good question, the MPG on the computor says average of 39mpg, but it definately is telling lies. Is that common?

Yes it is, do a search on how to recalibrate OBC. Yours if at 1000 should be set to 1194 to correct it, though you may need to fine tune a few times. Formula is: actual consumption in l/100km / OBC consumption l/100km x current correction factor (normally 1000 if not previously adjusted)

[djgandy]

Originally Posted by Pearler

Thanks for the posts.

the thermostat was found to be faulty a couple of weeks ago and both the EGR and coolant stats were changed, the engine is running up at 90degs C now which is good. So I was expecting an improvement. No other faults stored or shown on the ECU when it was in the garage.

I have 9miles to the office 3 times a week on 60mpg roads but normally can't get over 50 as there are a lot of Honda Jazzs in the area. I have to travel to another building 3 times a week which is about 24 miles is dual carriage way, cruising at 80-85 mph.

Was expecting better out of it but if this is the way it's gonna be I'll suck it up, like my fuel pump.

Theres your problem. 85mph uses a lot of fuel. 85mph is twice the air resistance of 60mph. Try sticking to the speed limit and see what you get.

[OGM2LCI]

Originally Posted by Pearler

Good question, the MPG on the computor says average of 39mpg, but it definately is telling lies. Is that common?
No smoke on start up. I've had a look out the back at night as well to see if there is much smoke in car headlights with quick aceleration, literally no smoke at all. Seems to run cleanly.

I'll check the breather pipe, cheers James.

My computer will often say anywhere in between 41-43 whereas when I work it out by brimming the tank, reset the trip computer, the next time I refill I take note of how much I put back in until the pump clicks and the miles driven using that amount of fuel will be on my trip computer, that usually gives me anywhere between 38-40mpg

[Nickos]

mines averaging 36 at the moment which isn't too bad considering I've been doing a lot of non motorway miles.

[pmmcbl]

I think your average is ok considering your town driving. And when you get on the motorway you not helping by driving at 85mph. Don't forget you have 6 cylinders.

In comparison I drive a 335i. In town I get 20 to 25mpg at best. Once on the motorway I get 35mpg if cruising at 80mph, if I drop to 70mph the mpg jumps to over 40mpg.

[Pearler]

Originally Posted by pmmcbl

I think your average is ok considering your town driving. And when you get on the motorway you not helping by driving at 85mph. Don't forget you have 6 cylinders.

In comparison I drive a 335i. In town I get 20 to 25mpg at best. Once on the motorway I get 35mpg if cruising at 80mph, if I drop to 70mph the mpg jumps to over 40mpg.

Thanks pmmcbl. I don't do town driving. I work in Suffolk, my route 9 miles has about 1 mile of that in 30mph zone.

My 24 mile route has about 1 mile of 30mph zone too. And rarely come to a stand still on either of those 1 mile sections, pretty provincial here! These ain't busy towns

[Jeff123]

Put a tank of decent fuel in it and take it for a good drive on a relatively clear motorway, maybe 50 miles. Once these cars are warm, the MPG really improves. Drive around the speed limit and aim for economy (on this occasion). You should be close to 50 MPG if it's an auto, more for a manual. If you get this MPG, the car is probably OK. The car computer should be pretty accurate, so zero the MPG it first.

[Pearler]

Originally Posted by apollo

Yes it is, do a search on how to recalibrate OBC. Yours if at 1000 should be set to 1194 to correct it, though you may need to fine tune a few times. Formula is: actual consumption in l/100km / OBC consumption l/100km x current correction factor (normally 1000 if not previously adjusted)

Thanks Apollo, I have a pop at that in the near future. have found full instructions on Bimmerforums.

I'm driving a 45 mile trip tomorrow, I'll stick to 70 on the duals and see how that goes.

[smithy79]

Up to two weeks ago I had a 325d for two years. I used it daily for my commute, the drive was 19miles each way. It was mainly dual carriage stuff at 50mph and a bit of start stop with traffic lights. I found it hard to get over 35mpg, and it usually dropped to 33mpg in the winter. That was trying to be economical with upshifting early in manual. I would say your about right with your mpg.

[Pearler]

Thanks for all your comments so far, appreciate the view and opinions.

So yesterday I had 47 mile run. 9 miles oof 60 limit and the rest dual carriage way with a few roundabouts. 1.5miles in 30 zones at the end of the journey.

I drove like Miss Daisy, in my socks and never broke the limit. cruised at 70 on the dual c's. Computer said averaged 42mpg over the total of 94 miles. We know it is inaccurate so given what I know I reckon it was averaging about 36.

I was expecting more!

I feel a remap to flatten out the power curve to get good performance in the lower rev range and improve consumption is on the cards soon...

[pmmcbl]

But remember the temperatures dropped loads over the last few days. The computer wouldn't be that far out. On my 335i I will be 2mpg out when comparing the dash vs calculator.
Now we are getting no more than 6mog during the day, it will take a lot long for the Diesel engines to warm up. What is the official urban and combined for your car? I always find the urban is what I get on average but all dependent on the temp.
I had a 2.0 tdi 170 Passat and that was running around 36 if driven around town, 45 with a mix and over 50 on the motorway at no more than 70mph.