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Fuel Economy

11K views 90 replies 54 participants last post by  TeenWolf 
#1 ·
From a full tank I'm getting around 380 miles. A mix of local and motorway driving and it's been in Eco pro all the way.
The only reason I opted for a diesel was economy or I would have gotten an m140i

Since collecting the car on September 1st I've nearly gone through 3 full tanks.
Anyone getting similar mileage. BTW it's a 125D Msport sports-auto!
 
#52 ·
ste111 said:
Hi folks,

I'm new to the forum, recently invested in a 125i.

Generally really like the car the only thing i can't get my head around is the economy. On a 90mile dual carriageway at 70mph (on cruise control in eco mode) it does around 33mpg. On A roads generally going slowly and shift with the indicated the most i've ever had is 34mpg.

Is this normal?? Its not a big issue as i don't do many miles but I cant understand how it has the same economy as my mates 10year old megane 225. Would appreciate some input from anyone who has one as i have read some people posting high 30s on long trips.
You could try some different fuel. I've always used Shell, but Shell, ESSO and BP regular fuels are of a higher standard than supermarket crap that's mixed with bio fuel. You might also want to try some of the premium fuels, I hear Tesco Momentum is supposed to be good, but whether it's still contaminated with vegetable oils I can't be sure. Back when V Power was only a few pence dearer than normal fuel I used to run my Clio 182 on it, I gained enough MPG increase to more than compensate for the extra few pence per litre - so it was actually cheaper to run.
 
#53 ·
I also have a 125i and unfortunately the fuel economy isn't as good as the brochures say. When I was looking for mine, the combined mpg figures shown in a BMW brochure were 42.8mpg.

I am a very light footed, smooth driver and my average is showing just above 34mpg.

I haven't done much long distance motorway driving yet, but from the little I have done, it seems to creep up towards the high 30s/early 40s in eco mode.

I too thought a newer more fuel efficient engine would have been better on fuel economy, but I wouldn't have bought the 125i if I was looking for pure fuel economy I suppose.

Edit; Mine is now running around 38mpg.

Sent from my SM-N9005 using Tapatalk
 
#54 ·
DodgerC said:
I also have a 125i and unfortunately the fuel economy isn't as good as the brochures say. When I was looking for mine, the combined mpg figures shown in a BMW brochure were 42.8mpg.

I am a very light footed, smooth driver and my average is showing just above 34mpg.

I haven't done much long distance motorway driving yet, but from the little I have done, it seems to creep up towards the high 30s/early 40s in eco mode.

I too thought a newer more fuel efficient engine would have been better on fuel economy, but I wouldn't have bought the 125i if I was looking for pure fuel economy I suppose.

Sent from my SM-N9005 using Tapatalk
Yeah, decent shout Andy, i think i'm going to fire some premium fuel in it. As you say hopefully get the cost back in millage.

Yeah, Dodger, it's interesting that you're still getting high 30/ early 40's on long trips as that was what i was hoping/expecting. Anything over 35mpg seems quite literally impossible even when you're only using a few of it's ponies cruising around. Tried all the usual tricks like full service, tyres and injector cleaner can't think mechanically like there could be anything else and although 100% subjective it seems to pull well. Maybe the 45k miles have worn it down a bit.
 
#55 ·
Mine is still low mileage at the moment, but I do use shell v power in it everytime, so might be worth a few tanks of that and see what happens as mentioned above.

The only time I really use eco mode is in traffic or long motorway journeys, otherwise I'm usually in comfort for everyday driving.

Sent from my SM-N9005 using Tapatalk
 
#56 ·
Hi from a new joiner.
I just picked a used 125i yesterday, 24mpg driving it back locally.
But I know I wasn't changing up soon enough, the gearing is definitely shorter than what I was used to, having previously had an E36 M3 since the turn of the century. The M3 used to do around 27 mixed and 30Mpg on a motorway run. Am hoping for a bit more from the 1er.
After all, the 125i is supposed to be sensible practical 5dr compromise.
 
#57 ·
21000 miles in my pre LCI 125D - getting 50MPG on mixed country roads, mostly taking it easy, but with moments of full power.
My Wife's 320D Tourer (2010 plate - 184BHP) - getting about 50MPG
My original 120D (54 plate - 163BHP) - used to get about 50MPG
 
#59 ·
Those are very respectable figures.

For anyone who's interested i figured out what was wrong with the economy in my 125i... as it turns out absolutey nothing. The onboard computer has obviously got high at some point and has lost all recollection on how to record fuel as the journey comp showed 34.1mpg but brim test 39-41mpg. :spotman: Happy now the 125 is living up to its all round duty's!
 
#60 ·
As someone else stated the greatest aid to fuel economy is to have the wife beside you !! Then I get around 50 mpg, on my own I get around 42 mpg. these figures on non congested out of town journeys. Suburban drops to around 35.
 
#61 ·
Using Fuelly to do brim-to-brim fills is the best method of assessing fuel economy.

Fuelly calculates the true mpg based on odometer readings and litres filled. The obc tends to overestimate the efficiency compared to the true brim-to-brim results, but by less than 5%.
 
#63 ·
Would be interested to know the MPG of someone with a M140 that lives in London.

In fact, maybe I shouldn't know......
 
#64 ·
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
 
#65 ·
DrewMsport said:
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
Are you driving faster than you used to?. The air resistance of a car is proportional to the square of the speed. Double the speed and air resistance increases by a factor of 4. At about 55 mph air resistance is about equal to all the other frictional drags on the car (tyres, engine etc). Above that speed air resistance increases rapidly and fuel consumption will decrease just as rapidly.
 
#66 ·
john1945 said:
DrewMsport said:
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
Are you driving faster than you used to?. The air resistance of a car is proportional to the square of the speed. Double the speed and air resistance increases by a factor of 4. At about 55 mph air resistance is about equal to all the other frictional drags on the car (tyres, engine etc). Above that speed air resistance increases rapidly and fuel consumption will decrease just as rapidly.
I dont think so, normally have cruise control set on motorway at about 72ish which is 2k rpm in 6th. (i like the revs sat on the 2k for some reason same as temp set to 22 degree on both sides.) and rest of drive is same 55-60 A roads and bit of 30mph through village zones where i always do 30, so speed has stayed the same. there was a section on bypass that had average speed cameras set at 50mph which has now gone, but surely 5 miles a day of doing 70 instead of 50 through there isnt dropping me 100 miles a tank???
 
#67 ·
DrewMsport said:
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
I appreciate it wouldn't account for this much of a difference especially as you're doing long journeys but the cold weather can noticeably reduce you miles per tank due to extended warm up times (and possibly the increased power output in really cold conditions). In the old tdi i think it probably wasn't far off about a loss of 5mpg so around 10% and that was on longer journeys in summer v winter
 
#68 ·
I upgraded from a 1.0l Hyundai i10 4 months ago and in my 2016 218i (1.5l) I'm consistently getting 5mpg below what I was getting in the i10, which isn't too bad really considering the BMW has half the 0-60 time and more than double the torque and horse power.

99% of the time I just leave it in comfort mode and I'm currently averaging about 35mpg in rush hour city driving (compared to 40mpg in the i10) and 45-50mpg on a motorway run (compared to 50-55mpg in the i10).
 
#69 ·
ste111 said:
DrewMsport said:
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
I appreciate it wouldn't account for this much of a difference especially as you're doing long journeys but the cold weather can noticeably reduce you miles per tank due to extended warm up times (and possibly the increased power output in really cold conditions). In the old tdi i think it probably wasn't far off about a loss of 5mpg so around 10% and that was on longer journeys in summer v winter
+1, the cold weather has a huge impact on MPG.

Engine takes longer to warm up, tyres take longer to warm up and the fact the air is colder means the engine should be producing more power - colder air = more power.

All these factors will hit your MPG in winter, but also improve performance!! ;)

My old 120d used to drop from averaging 37-40mpg in summer to about 32mpg in winter.

My M240 is currently doing about 16mpg around town, 33mpg on a run.
 
#71 ·
My first quarter tank in the m235 since the cold hit and I'm averaging 24mpg! :eek2: Hopefully this rises before the tank is empty, I can't live with a tank average of 24mpg when I haven't been "pressing on".
 
#72 ·
DodgerC said:
I also have a 125i and unfortunately the fuel economy isn't as good as the brochures say. When I was looking for mine, the combined mpg figures shown in a BMW brochure were 42.8mpg.

I am a very light footed, smooth driver and my average is showing just above 34mpg.

I haven't done much long distance motorway driving yet, but from the little I have done, it seems to creep up towards the high 30s/early 40s in eco mode.

I too thought a newer more fuel efficient engine would have been better on fuel economy, but I wouldn't have bought the 125i if I was looking for pure fuel economy I suppose.

Sent from my SM-N9005 using Tapatalk
Is this the f20 125i? I was getting 40 mpg on mways in comfort mode, without even thinking about it and whilst enjoying the car.... :cool2:, so suspect it could do better. Around town it was around 30, worse case 28.

Always used v-power or momentum.

My m240i, by comparison, is simply shocking - as low as 22 and around 24 on anything other m/ways (though still being run in).
 
#73 ·
Are bmw engines known for the significant decrease in fuel economy in the cold? Ive been driving 15 yrs and havnt noticed such a variation in other cars. As someone stated they lost 8mpg just because of the temp? Very strange. Luckily i do long drives sonthe engine spends more time at temp.
 
#74 ·
My old Focus ST did the same, one winter I had it down to 11mpg on my short commute! :D
 
#76 ·
OneTwenty said:
ste111 said:
DrewMsport said:
My mpg seems to be going down? I do the same drive everyday for work, 94 mile roundtrip, and i was getting 60mpg to start and about 580 fill to fill on the trip computer as i reset every time i fill up. Which with personal mileage ment aswell as work trip one tank was doing me 7 days amd have been happily in a routine of filling up every friday on way home from an early finish. This tank however ive managed 460miles, but it has been steadily dropping the past few weeks down to 550, 520, 500 etc but this 460 seems rather bad. I could get 400-420 out of my civic type r fn2, 2.0l petrol. Anyone have an explanation for this? I thought as engines bed in they were supposed to get better? I now have 22k on and my best mpg results were at 15k. I certainly hope this hasnt settled into its lifetime range now.
I appreciate it wouldn't account for this much of a difference especially as you're doing long journeys but the cold weather can noticeably reduce you miles per tank due to extended warm up times (and possibly the increased power output in really cold conditions). In the old tdi i think it probably wasn't far off about a loss of 5mpg so around 10% and that was on longer journeys in summer v winter
+1, the cold weather has a huge impact on MPG.

Engine takes longer to warm up, tyres take longer to warm up and the fact the air is colder means the engine should be producing more power - colder air = more power.

All these factors will hit your MPG in winter, but also improve performance!! ;)

My old 120d used to drop from averaging 37-40mpg in summer to about 32mpg in winter.

My M240 is currently doing about 16mpg around town, 33mpg on a run.
Also, have you recently changed tyres? I noticed a drop moving from my summer to winter set but not overly significant. Lifetime MPG reading drops 0.1 on the winters then returns to an indicated 29mpg on summers. Manually calculating that's more like 27 - 31 mpg tank to tank.
 
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