[Piers]

Reading all the consumption stories on here, I thought I would do my own experiment.

Car has 3,300 miles on LCI 520d

One tank brimmed, computer mpg reset. 50/50% motorway and town

Did 582.5miles, with 10 mile range left.

Computer said 43.1mpg ( which is better than I had been getting)

Filled it to the brim today and did the calculation.

66.05 litres to fill - gives me real world consumption of 40.1mpg

BMW computer is 7.5% out in their favour

I drove it like a nun most of the time to see ( which is difficult of 582.5 miles!!)

Tbh I am not impressed, not even slightly. It is not the money but the principle that the BMW quoted figure of combined 50mpg is a pipe dream.

[HighlandPete]

Originally Posted by Piers

Reading all the consumption stories on here, I thought I would do my own experiment.

Tbh I am not impressed, not even slightly. It is not the money but the principle that the BMW quoted figure of combined 50mpg is a pipe dream.

The problem is not strictly BMW, (they can't legally quote any other figures), but the way the NEDC test does not reflect real world driving, has got so adrift from user experience, and this applies across the marques. Clearly all the manufacturers are now designing to meet the highest figures possible from the NEDC test. Same happened in the old test regime. MPG Shortfall is something we have to live with, until the EU put together a more realistic test regime. It is just what percentage to knock off, when we go buying a new car. Used to be ~11% about 10-years ago, crept up to ~15% and now moving towards a 20% average.

The 520d with its ECO features will have a mpg shortfall of around 15 - 20% (from the combined figure) in average driving.

Your mileage is still low, get past 10k miles and you will likely see improved mpg.

HighlandPete

[Beancounter_74]

I'm wondering that even though it shouldn't, is the auto box hurting the mpg.
Did you use Eco Pro at all?

I've been tracking my mpg with Fuelly.com since the first fill up (after the miserly £40 from the dealer ) and with mostly city driving (more than 80%) I'm getting 39.2 when I last checked for the 3,200 miles I've done.
......But on a motorway run to South Wales just before Christmas, I got 725 miles out of a brimmed tank (20 left on the display) so very high 40's.
That was cruise on at 75 mph as the weather was shocking with high winds and just me in the car and Eco pro on for say 70% of the journey. I expect that to improve as the car loosens up though.

[Piers]

HighlandPete, you are right of course.

Beanie, the auto will come into its own on long journeys, not sure if it hampers town driving, I cannot see how the manual could save any as the auto is faultless in its rpm changes.

My colleague has a pre LCI sports auto 520d, drives it like he stole it everywhere and gets a similar mpg, mostly better though.

On the motorway run I did I was at 69mpg with a full tank over 75miles, it's the town stuff that genuinely kills the mpg!

Still an awesome car though, and 40mpg with all this quality and weight is still very impressive, so wouldn't change it!!

[Beancounter_74]

I hear you Piers.

I must admit, mpg is not something I'm concerned about despite me tracking it on Fuelly (a sweeping statement I know). I came from a RRSport and was lucky to see anything over 25mpg and to do that I had to drive like the said nun! Any sign of using my right foot could easily see that number drop to 'teens

[HighlandPete]

If the motorway figures are good as is indicated, then we are back to the old chestnut of "big car, small engine" for stop-start driving.

Our 5-series are heavy cars and mpg will suffer, continually hauling them off the line, it is simple physics.

I suggest there isn't much difference between a 520d and 530d in heavy urban driving, even my 535i won't be too far behind, for that matter. The 520d needs more throttle and more turbo boost to get it up to speed, than the bigger engines, if we drive in a similar manner.

Where the 520d gains is at sensible cruising speeds, where the diesel sips fuel. So 520d users see a massive swing in mpg according to use. Drive a bit faster and the same applies as town driving, the 530d starts levelling on fuel consumption.

Something like my 535i has given a 30+mpg return over the last 10k miles, with less than 20% motorway use. So mostly local and mixed driving. But drive on the motorway and I won't see a big change, may peak ~35mpg on a good run. My typical working range is 28 - 33mpg. I sense in a 520d you will see a working range something like 30 - 55mpg, possibly even more extremes.

I've experimented in an F30 320d ED, again the mpg variation (due to use) is wide, in light local but rural driving ~50mpg to over 74mpg at a steady A road cruise. What would the working mpg range be if heavy urban was added? 35mpg to 70mpg, very likely.

HighlandPete

[xs2man]

Well, thought I would add my experience here. I think I have missed one fuel up since getting the car. Something like 4500 miles done since new. 530d M-Sport with Sports Auto...

model mpg miles litres price notes
BMW 530d 37.3 537 65.37 1.369 First Fuel Up...
BMW 530d 40 576 65.491 1.359 39.7 OBC
BMW 530d 39.6 579.1 66.559 1.357 40.2 mpg indicated
BMW 530d 37.8 481.3 57.951 1.379 38 mpg indicated
BMW 530d 36.6 507.3 63.001 1.379 36.2 MPG Indicated. Mostly Highway
BMW 530d 38 554 66.248 1.359 38.5 mpg indicated
BMW 530d 36.9 550 67.77 1.339 37.5


Thats an export from my fuelly, and is probably formatted all wrong here. But I have tried to be reasonably accurate here.

Averaged 38 mpg overall, so not bad. MOSTLY driven in ECO PRO mode to be fair, as most of my journeys are out of necessity, rather than for fun, so never in so much of a hurry. Although I do occasionally boot it while in Sports mode.

Anyway, I always reset the trip computer when I fill up, and take a note of the OBC value, and enter it as a not in Fuelly. Generally average speed over the tank is 35-40 mph, so while there is a lot of out of town driving, there is also a lot of town driving. So a fairly average mix up.

As you can see, OBC is close enough to real figures, it is hardly worth distinguishing between them.

As for comparing values to BMW values, well that's a waste of time. Take the urban figure, and take 10% off. The way they do the tests is on a rolling road, with items like the brakes and stuff removed, and is basically a completely unrealistic test that could never be repeatable in real world. I learned this the hard way with my Audi buying a few years ago.

Now, I have realistic goals. Ideally I would like to start with a 4X on my MPG, but so long as it's better than my 335d which gave 37.6 over 18k, I'm happy enough. It is a bigger, better spec'd car afterall.

[SomeRandomer123]

You can actually alter the correction factor (K Factor) in the hidden OBC menu. I have a video here of how you can access it but you'll have to figure the correction factor yourself

[u2b]https://www.youtube.com/watch?v=TFJdW4Hy0yM[/u2b]

[accordRE]

I had a test drive in an LCI 520d with auto and paddles and I had 1/8th of a tank to begin with, put a gallon in at Shell went for a motorway cruise, averaged 56mpg. Filled the car up when it had 814 miles on the odo and gave it back with 870 miles and an eighth of a tank.

On an unrelated note, what a car!

[SpeedTrip]

Originally Posted by SomeRandomer123

You can actually alter the correction factor (K Factor) in the hidden OBC menu. I have a video here of how you can access it but you'll have to figure the correction factor yourself

[u2b]https://www.youtube.com/watch?v=TFJdW4Hy0yM[/u2b]

Does the 5ver F10/11 have a hidden OBC menu-set too ?

[SomeRandomer123]

Originally Posted by SpeedTrip

Does the 5ver F10/11 have a hidden OBC menu-set too ?

It certainly does, and the user interface is almost identical to what you see there in my F30.

[gIzzE]

Originally Posted by Piers

Tbh I am not impressed, not even slightly. It is not the money but the principle that the BMW quoted figure of combined 50mpg is a pipe dream.

Combined is a mean average of the urban figure and extra urban, which is 7km averaging 39mph.

Unless you drive at 39mph then forget combined.


I tend to look on the us sites now for MPG figures, their city and highway figures are far closer to real world, and seem to match what owners on fuelly etc. get pretty much.

Remember to convert back to UK gallons though.

[Piers]

Gizze, funny you should raise this, I was going to put so more figures on. My colleague drives the same car, 520d MSport," like he stole it " everywhere, and gets the same or MORE MPG than I do....he has 20k on his, mine is 4k, so maybe that is the difference.

In case anyone is interested -

Tank 1- Did 582.5miles, comp said 43.1, actual calc 40.1mpg.
Tank 2 - Did 530 miles, comp said 39.6, actual calc 37.7mpg.

BMW computer is 7.5% then 5% out in their favour.

More stop start this tank.

[gIzzE]

Just trying to find a comparison of a diesel on the US site vs UK site.

USA 535d vs 535d UK

USA is 45mpg Highway (converted to UK gallons)

UK 60.1 extra urban


Which owner do you think is more disappointed?

[NigeNige]

Originally Posted by Piers

Gizze, funny you should raise this, I was going to put so more figures on. My colleague drives the same car, 520d MSport," like he stole it " everywhere, and gets the same or MORE MPG than I do....he has 20k on his, mine is 4k, so maybe that is the difference.

In case anyone is interested -

Tank 1- Did 582.5miles, comp said 43.1, actual calc 40.1mpg.
Tank 2 - Did 530 miles, comp said 39.6, actual calc 37.7mpg.

BMW computer is 7.5% then 5% out in their favour.

More stop start this tank.

I used to keep a full record in the 1st few years of ownership of my E 60 530d M Sport. Here is a graph of the results. The journey computer always shows about 10 mpg better than actual, rubbish if you ask me.

I have now done 120,000 miles and am about to change to new F10 520d Luxury (with toys). I will take a similar record so we can compare. I hope to get much better than the old car

[NigeNige]

I have seen an interesting video on you tube where it shows you how to adjust the accuracy of the displayed mpg. (about 2 minutes into video)

I would be interested to hear if anyone has tried and been successful with this. Also will this work with the multi function display?

Nigel

[Johnny Grabble]

Yes. Done this successfully. OBC was about 6% optimistic on my F10, so I went into the menu and changed it. It's now 99% accurate compared to the brim to brim calculation.

[xs2man]

My LCI F11 (530d mind you) is almost spot on.

Last tank was an indicated 41.1 MPG (average speed 38.8 mph). And stuck the details into Fuelly and it spat out a 41.4 MPG.

It's always within 0.6 MPG of actual calculated values. But can be either up or down of the calculated value, so +- 0.6 mpg accuracy or +- 1%