[325_bucks]

I love my G31, everything about it is exactly what I need for the family and the perfect companion to my M6. Problem is, my M6 is getting me better MPG, or at least almost identical MPG, than the 540i.

This is the case on a basically the same roads and journeys. I'm getting around 18.2mpg in the M6, I'm currently sitting at 18.7mpg in the 540i. I know I'm not the lightest footed driver, but I've been extra careful with it to see what it can do, and I'm confused.


Is this the expected consumption if purely doing short local driving? If it is, that's ok, I just want to make sure it's not wrong. Low 20s I would have said was borderline personally, but 18s seems too low. There is nothing wrong with the car, no errors, yes it has the MPPSK but this is claimed to not reduce MPG at all.

Any ideas?

[SteveinArizona]

Short local driving will certainly negatively impact on your mpg. But I would have expected an M6 to be worse.

[325_bucks]

Originally Posted by SteveinArizona

Short local driving will certainly negatively impact on your mpg. But I would have expected an M6 to be worse.

So would I! that's the concerning thing. It could just be my driving profile but in the M6 doing the same journeys I can easily hit the figure above, whereas it seems to be a struggle to keep the 540i in that range

[LogicalApex]

What MY and what sort of roads? Also what driving mode do you typically use?

I don’t have a 540i so I can’t comment authoritatively, but the additional information will help those in the future hunting this down or assessing the fuel economy of the 540i.

[325_bucks]

Originally Posted by LogicalApex

What MY and what sort of roads? Also what driving mode do you typically use?

I don’t have a 540i so I can’t comment authoritatively, but the additional information will help those in the future hunting this down or assessing the fuel economy of the 540i.

It's a late 2017 car, think it might be a MY18 but not sure. I normally drive in comfort, recently I've been trying Adaptive which I didn't think would make a difference to economy but it might have had a very slight positive effect but nothing substantial. I've only had the car since mid December so I can't compare it to the past to know if it's changed for example.

[ztx84]

Town driving with the 540 does result in really poor economy. I have seen very low 20s and that is being very careful in town. On a run it is good, but around town - shocking. To give some perspective I achieved 550 miles from a tank with lots of motorway driving, and just over 350 from a tank when I was pretty much only around town. A huge difference!

[dberry08]

I get about 23mpg with mostly highway driving, typically in sports mode in my 540i.

[SteveinArizona]

Originally Posted by 325_bucks

It's a late 2017 car, think it might be a MY18 but not sure. I normally drive in comfort, recently I've been trying Adaptive which I didn't think would make a difference to economy but it might have had a very slight positive effect but nothing substantial. I've only had the car since mid December so I can't compare it to the past to know if it's changed for example.

In terms of mpg adaptive should be pretty similar to comfort. What mode do you use when you drive the M6?

[Qsilver7]

What is the average MPH (miles per hour) for each vehicle when you look at the figures in iDrive? Is the MPH for each vehicle the same or similar? If they are not...then even though you're driving on the same roads...somehow your average MPH is different which will also affect the average MPG.

[325_bucks]

Originally Posted by SteveinArizona

In terms of mpg adaptive should be pretty similar to comfort. What mode do you use when you drive the M6?

A mix but usually my M1 button which is configured as sport engine, gearbox 2, sport dampers and steering.

[325_bucks]

Originally Posted by Qsilver7

What is the average MPH (miles per hour) for each vehicle when you look at the figures in iDrive? Is the MPH for each vehicle the same or similar? If they are not...then even though you're driving on the same roads...somehow your average MPH is different which will also affect the average MPG.

That’s a good point, I will check that but I suspect my average mph will be higher on the M6

[SteveinArizona]

Originally Posted by 325_bucks

A mix but usually my M1 button which is configured as sport engine, gearbox 2, sport dampers and steering.

Now I am puzzled. If you are driving in sport mode in the M6 and comfort or adaptive in the 340, you should do worse on the M6. Something does seem to be wrong.

[325_bucks]

Originally Posted by SteveinArizona

Now I am puzzled. If you are driving in sport mode in the M6 and comfort or adaptive in the 340, you should do worse on the M6. Something does seem to be wrong.

Yeah exactly, just need to find out what it is!

[KoenG]

Originally Posted by 325_bucks

Yeah exactly, just need to find out what it is!

It's rather impossible that an M6 demonstrates an equal frugality than the 540i! Never! The M6 is prepared for full attack assaults of 600hp, while a 540i is clearly down tuned for fuel efficiency and the mppk doesn't change this!

The 540i should really make a (big) difference when idling for the stoplights in the city, or when you don't call the power. The compression ratio is 10% higher than the one on the M6, so even when you call the same power, it should be about 10% more efficient.

Also consider that a V8 suffers more from "pump & inertion losses" ... so I would double this 10% to 20% in favor of the 540i mppk.

[HighlandPete]

Originally Posted by 325_bucks

Any ideas?

How hard are you driving the 540i, compared to the M6. Having MPPSK gives a clue.

Are the figures calculated, or simply OBC? OBC tolerances could simply be skewing the figures.

xDrive losses will have to be factored in for the 540i. Remember the harder you drive, the more that stacks against you.

A more powerful vehicle doesn't always mean worse mpg, in similar driving situations. Proven over and over through the years.

[g11730d]

Originally Posted by dberry08

I get about 23mpg with mostly highway driving, typically in sports mode in my 540i.

Is that US MPG? That would be about 27-28 Imperial MPG which is quite impressive.

[cartaozinho]

Originally Posted by dberry08

I get about 23mpg with mostly highway driving, typically in sports mode in my 540i.

Sport mode must really kill the fuel consumption...on longer family trips (in Comfort) I've averaged just short of 30 mpg (29.8, if memory serves)...and that's in an M550i!

[325_bucks]

Originally Posted by HighlandPete

How hard are you driving the 540i, compared to the M6. Having MPPSK gives a clue.

Are the figures calculated, or simply OBC? OBC tolerances could simply be skewing the figures.

xDrive losses will have to be factored in for the 540i. Remember the harder you drive, the more that stacks against you.

A more powerful vehicle doesn't always mean worse mpg, in similar driving situations. Proven over and over through the years.

I suppose I drive the 5 a little harder than average but not regularly and the MPPSK was fitted previously so I didn’t put it on myself. The figures are OBC and I guess I do need to take into account xDrive losses and obc tolerances, but that’s why I guess I wanted to see what other people’s OBC was saying.

[Max_M]

Well don't forget its winter time now and that makes a difference of approx. 10% in fuel efficiency.....