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Discussion Starter · #1 · (Edited by Moderator)
I'm fully aware the F40 M135i isn't exactly a car you buy to achieve good mpg.

That said, my 1-year-old car, which has covered 11k miles of mixed driving and roads, is achieving long-term mpg of 27, according to the computer.

That said, I think this is even way off. For example, I put 拢40 in on Thursday, and the car was down to the reserve tank yesterday, having covered nowhere enough miles to warrant the reduction in fuel (even despite the obvious fuel prices, something isn't right).

The oil level is fine, tyre pressures are slightly below what BMW recommend for the tyre wear issue, but I cannot fathom how this thing is literally drinking petrol so badly.

Has anyone experienced similar? The trip computer range is pretty pointless. I can fill the car, drive it economically somewhere, and the trip computer plummets like I've never seen in any other car...

Whilst I'm probably selling the car this month, if I do keep it, the tyres would be getting changed to PS4s, and I'd be doing a service well before the scheduled 18500 and would hope at least some improvement is found 馃ぃ
 

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I don't think you are being scientific enough about this for anyone to give any sensible response. Without knowing how many litres that was or how many miles you drove, "putting 拢40 in and being down to reserve in a few days" doesn't give any meaningful information.

You need to brim the tank, drive until it is on reserve, brim it again and note the miles travelled. Then you can work out your actual mpg for that tank and find if it matches what the trip says and if it is a reasonable value.

On the trip system in idrive you can set the system to automatically reset when you refuel and then the trip gives you an average mpg since then, so you can compare that to your calculated value.

FYI my M135i has averaged 34.6mpg since I last filled up.
 

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Discussion Starter · #3 ·
I don't think you are being scientific enough about this for anyone to give any sensible response. Without knowing how many litres that was or how many miles you drove, "putting 拢40 in and being down to reserve in a few days" doesn't give any meaningful information.

You need to brim the tank, drive until it is on reserve, brim it again and note the miles travelled. Then you can work out your actual mpg for that tank and find if it matches what the trip says and if it is a reasonable value.

On the trip system in idrive you can set the system to automatically reset when you refuel and then the trip gives you an average mpg since then, so you can compare that to your calculated value.

FYI my M135i has averaged 34.6mpg since I last filled up.
Thanks Geoff - and yeah, appreciated some basic data is missing, but I'm not talking days, I'm talking a day, and I drove from Newcastle to Durham and back, which is circa 50miles, with stops along the way.

I'm definitely going to brim the car and calculate the real MPG if it hasn't gone by the time I do so 馃檮馃お
 

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Discussion Starter · #6 ·
Something definitely isn't right with it.

I didn't buy the car for efficiency, but the readings and trip computer seem absolutely miles off, especially factoring in how I drive.

Will see how this tank goes and work it out again.
 

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I do I similar trip to you, I travel from Durham to Newcastle daily & average around 40 mpg for the week 350 miles from a full tank and that鈥檚 filling up before the fuel light comes on, maybe 400 if I wanted to run it lower. That鈥檚 bearing in mind sitting on the A1 south car park during rush hour of cutting through Birtley
 

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On a long motorway drive in eco and cruise control at 70 I managed 34 mpg. When driving normally in comfort (mainly city but some motorways) I get around 23 mpg. I only use Tesco 99 momentum
 

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On a long motorway drive in eco and cruise control at 70 I managed 34 mpg. When driving normally in comfort (mainly city but some motorways) I get around 23 mpg. I only use Tesco 99 momentum
Wow. That can鈥檛 be right. A 3l m140i would be getting over 40mpg on the motorway and around the same as you or better in town.
 

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I have averaged 6.7l/100km (42mpg) over 24000km. I do 90% highway driving. Initially the car was less economical showing 8.7l/100km (32mpg) after the first 5000km. I drive it in eco on the highway and comfort in town. 34mpg on the highway is probably OK but not great. In eco mode you can see the instantaneous fuel consumption on the dash, you should be able to achieve a bit over 5l/100km (47mpg) on a flat road.
 

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Discussion Starter · #13 ·
These cars are seriously thirsty.

I'm not being naive here, for a modern 2.0 turbo, they're truly awful. As I said earlier, I didn't buy it for economy, but if I wanted this level of thirst from a car, I'd have gone for something that didn't sound like a Hoover.

It may be there's something else contributing, in my opinion an oil change and new tyres will obviously help albeit tyres aren't ready to go yet, but with my varied driving and over the course of 12,000 miles to be returning a long term 27mpg is woeful.

If the car made a nice sound, as daft as it sounds I could see a small compromise there - but it doesn't. Add in the numb steering and styling which hasn't grown on me in the past year, and I'm ready to part with it.

The longer test drive I had in the new M240i was looking like it was achieving better economy sitting on a dual carriageway. I would expect something like that with the B58 to be averaging low to mid 20mpg, but I'm fairly sure I've seen many people get better than that! The long term mpg in that demo car was close to mine, and that's with weekly thrashing from customers and salesmen馃ぃ
 

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Seriously thirsty, I think you might have an issue mate. Mine is pretty much on par with my past 2018 125d on mpg
My 18 mile commute to work regularly gets 50+ mpg in the summer and that鈥檚 from a cold engine
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I came from a cupra 290 and my commute to and from work is all B Roads.

With sensible driving, I managed a peak of 45mpg in the cupra, but when I switched to the M135i I can get 52mpg in the same journey. (and that's in a brand new car, I imagine it might get better?)

So I'm very impressed, personally.
 

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new tyres will obviously help
What makes you think new tyres will help mpg? Providing your current ones are at a sensible pressure unless you switch to an eco focused tyre I don't think tyres will make much difference. In fact it's possible that a new tyre with deeper tread might actually have a slightly higher rolling resistance than a part worn one, as there is more tread block movement wasting energy. I think the effect will be very marginal either way though and don't think it accounts for your problem.
 

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On a motorway run, sitting at 75mph, mine will return mid-40s mpg all day long. On a long run like this, I can easily get 400+ miles to a full tank.

In the city, I only get 25(ish) mpg as it鈥檚 all stop/start short journeys where the car can barely get up to temp. City-driving, I get between 200 & 250 miles from full.

I run mine on Tesco Momentum 99 (as it鈥檚 the closest station to me) majority of the time. Shell V Power & BP Ultimate have produced identical figures in my experience.
 

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Discussion Starter · #19 ·
What makes you think new tyres will help mpg? Providing your current ones are at a sensible pressure unless you switch to an eco focused tyre I don't think tyres will make much difference. In fact it's possible that a new tyre with deeper tread might actually have a slightly higher rolling resistance than a part worn one, as there is more tread block movement wasting energy. I think the effect will be very marginal either way though and don't think it accounts for your problem.
Fair, albeit we're both splitting hairs.

I just don't think the Bridgestones are good at anything and so Michelin etc could only improve things, mainly because they could be set at the "right" pressure, without the uneven wear issues of the Bridgestones.

Point being having to run a lower pressure to combat uneven wear has the compromise of mpg.... possibly... but of course, it's negligible
 

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Thanks Geoff - and yeah, appreciated some basic data is missing, but I'm not talking days, I'm talking a day, and I drove from Newcastle to Durham and back, which is circa 50miles, with stops along the way.

I'm definitely going to brim the car and calculate the real MPG if it hasn't gone by the time I do so 馃檮馃お
A lot depends on how you drive.

If I drive 50 miles I can get the car to do 18mpg, or I can get it to do 35mpg. It literally depends on what mood I'm in, and how I drive it.

Just to add, when I moved from MPSS to PS4 tyres, my MPG went down by about 4mpg - because the outright grip was better in all weathers, especially when wet, I was driving faster and using more juice. Now I have an intake fitted, that figure has gone down again as the noise is addictive so I boot it more. :ROFLMAO:
 
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