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mpg - any help would be great

1K views 20 replies 10 participants last post by  CAM4V 
#1 ·
Is 25 - 28 mpg good for this time of the year??

In the summer I usually do about 32 mpg so seen a bit of a decline and dont know if 25 mpg is too poor for my car?

Had my MOT last week and emissions past, so dont think it is that - so think it may be Ok but just want to check as my petrol seems to go down so quick, putting in £30 every 10 days :(

CO - 0.30%
Lambda - 1.03

Thanks,
 
#4 ·
Efficiency largely depends on the kind of driving u do.. short journeys are less efficient cos ur usually in the lower gears and the engine is also running cold for a greater proportion of ur drives.. Ur driving style also makes a huge difference, try to avoid foot to the floor at all times if poss, try to keep the car under 3000 revs, especially during the first 10 mins of driving (While the engine heats up).. check tyre pressures weekly.. Stuff like that makes a diff..
I got a R214, I can get an extra 5mpg out of a tank when I follow these steps.. try 'em out!
What kind of driving do u do routinely??
 
#8 · (Edited)
E_T_V said:
yes it depends on you jouneys and style of driving. If is it lots of short start stop journeys round town in traffic etc then that is certainly possible. however you should be getting high 30's on a good run.
Is it really that bad???? What could it be??? I had my mot last week and it passed? so dont know what it could be, my emissions were co 0.30% and lambda 1.03? passed ok? My main driving is 7 miles to work - 3 mile motorway, 4 mile stuck in traffic? could it be that? in the summer i get 33 mpg ? I put 36litres in my car, drive for about 210-220 miles (by now tank is down to just above red line) fill it up again which takes 36 litres and that by my working means 36 l is doing 210-220 miles which mpg is 25-28??
So what am I doing wrong or what could be wrong with my car, it does not smell of petrol?
 
#9 ·
25 mpg does seem very very low for ur engine but then again u do seem to be doin short ass journeys and bein stuck in traffic is killer on fuel too, all the time ur sat still the car's burning fuel and every time u get movin u have to rev up to get it goin so yeah, that could explain, if u're really worried why not plan a bit of a road trip one weekend? Get some friends together and take them somewhere that's a couple of hours drive away for xmas shoppin or somethin, fill the tank up before u go, drive sensibly, keep it at 70 tops on the motorway and avoild foot to the floor action and then when u get home, fil it up again and work out ur mpg.. Just to be sure, what equation ru using to work it out??
A gallon = 4.54 litres
So however many litres ur car takes, divide it by 4.54 to get ur gallons then divide the number of miles u've done by the number of gallons used... There's other ways of workin it out usin the same number but that's the way I do it
:)
 
#10 ·
projectgaz said:
25 mpg does seem very very low for ur engine but then again u do seem to be doin short ass journeys and bein stuck in traffic is killer on fuel too, all the time ur sat still the car's burning fuel and every time u get movin u have to rev up to get it goin so yeah, that could explain, if u're really worried why not plan a bit of a road trip one weekend? Get some friends together and take them somewhere that's a couple of hours drive away for xmas shoppin or somethin, fill the tank up before u go, drive sensibly, keep it at 70 tops on the motorway and avoild foot to the floor action and then when u get home, fil it up again and work out ur mpg.. Just to be sure, what equation ru using to work it out??
A gallon = 4.54 litres
So however many litres ur car takes, divide it by 4.54 to get ur gallons then divide the number of miles u've done by the number of gallons used... There's other ways of workin it out usin the same number but that's the way I do it
:)
Thanks, I am due to take one of my mates to Gatwick next Friday - thats 160 miles in total so that be good test, it does seem to do better when going onr uns, like when went to yarmouth last year I done 350 miles to the tank?? but since then it seems to have dropped despite passing the mot so think everything must be ok just bit concerned incase any problems get worse, thanks for your help!
 
#12 ·
I own a 99 416 and in winter my mpg drops from around 34 to 37 in summer to between 31 to 34 in winter. I've put this down to the following

  1. Car on choke longer
  2. More electrical load
  3. More traffic on roads especially comming up to christmas
  4. Hating dark mornings so I leave for work latter and so instead of taking 50 - 60 minutes to do 25 miles it takes me 80 minutes do the same journey.
 
#13 ·
projectgaz said:
25 mpg does seem very very low for ur engine but then again u do seem to be doin short ass journeys and bein stuck in traffic is killer on fuel too, all the time ur sat still the car's burning fuel and every time u get movin u have to rev up to get it goin so yeah, that could explain, if u're really worried why not plan a bit of a road trip one weekend? Get some friends together and take them somewhere that's a couple of hours drive away for xmas shoppin or somethin, fill the tank up before u go, drive sensibly, keep it at 70 tops on the motorway and avoild foot to the floor action and then when u get home, fil it up again and work out ur mpg.. Just to be sure, what equation ru using to work it out??
A gallon = 4.54 litres
So however many litres ur car takes, divide it by 4.54 to get ur gallons then divide the number of miles u've done by the number of gallons used... There's other ways of workin it out usin the same number but that's the way I do it
:)
Kool that means I'm getting around 35-37mpg out of my 1995 Rover 414 which compared to the 25ish I used to get out of my 1.8 Volvo s40 is not bad... and the Rover is faster too, with only 12bhp less !!
 
#14 ·
I have an '00 416iXL saloon. The fuel consumption doesn't change much, probably the extra winter loads are compensated for by not running the air con.
Anyway, best ever on a run was 49mpg (with aircon running)
Usual on a run is 44mpg (with aircon on)
Local journeys give high 30s but we live in a rural area so there's not so much stop/starting as other folks have and much of our running about is done in our 200.
 
#15 ·
Yeah, in winter obv the car runs on choke for longer BUT the air is cold and cold air is denser, so for every litre of air ur intake takes in there is actually more oxygen that if the air was warm so it actually runs leaner, ofcourse the air could have warmed up goin past the engine before it reached the intake, I'll shut up about that..
But anyway, driving STYLE plays a huge role in efficiency, avoid foot to the floor and try staying under 3000 revs and avoid harsh accelaration unless it's neccesary, I know this time of year u take any gap there is at some roundabouts or junctions so puttin the foot down is the only way but other than that, try to avoid it.. Like I said before, if ur worried there's somethin up with ur car, take it on a long run and drive easily and then test the mpg... U'll get a truer reading then..
:)
 
#16 ·
projectgaz said:
Yeah, in winter obv the car runs on choke for longer BUT the air is cold and cold air is denser, so for every litre of air ur intake takes in there is actually more oxygen that if the air was warm so it actually runs leaner, ofcourse the air could have warmed up goin past the engine before it reached the intake, I'll shut up about that..
But anyway, driving STYLE plays a huge role in efficiency, avoid foot to the floor and try staying under 3000 revs and avoid harsh accelaration unless it's neccesary, I know this time of year u take any gap there is at some roundabouts or junctions so puttin the foot down is the only way but other than that, try to avoid it.. Like I said before, if ur worried there's somethin up with ur car, take it on a long run and drive easily and then test the mpg... U'll get a truer reading then..
:)
Thanks, dont think there is anything wrong! having spoke to Major Ingram and Amagoza they say 25 mpg on driving etc I do is normal, so not worried about it anymore, the car passed the mot so must be OK!! as the readings were not even that bad! thanks for your help anyway. just gonner get on and keep filling up, if it drops to 20 mpg thats when will get it checked out, also got service next month so if there is any major problem, sur eit will come up then :)
 
#17 ·
projectgaz said:
Yeah, in winter obv the car runs on choke for longer BUT the air is cold and cold air is denser, so for every litre of air ur intake takes in there is actually more oxygen that if the air was warm so it actually runs leaner, ofcourse the air could have warmed up goin past the engine before it reached the intake, I'll shut up about that..
The air may be colder and denser in winter, but the lambda sensor keeps the mixture the exactly the same meaning that you burn the same amount of fuel for the same power delivery. (However you will get a little more power flat out in winter due to the colder air)
 
#19 ·
stevepilborough said:
Thanks, dont think there is anything wrong! having spoke to Major Ingram and Amagoza they say 25 mpg on driving etc I do is normal, so not worried about it anymore, the car passed the mot so must be OK!! as the readings were not even that bad! thanks for your help anyway. just gonner get on and keep filling up, if it drops to 20 mpg thats when will get it checked out, also got service next month so if there is any major problem, sur eit will come up then :)
Does it get up to heat quick enough? I'm thinking thermostat if it doesn't, that could be a possible explanation. To be honest I had a 1999 416i 2 weeks ago as a courtesy car, and it was a bit of a drinker too.

My 420 did 25 in winter, 28/30 Summer, on a 7 mile journey to work, and back. my 414 Sli never ever ever did anything less that 35, (same journey) my Volvo 740 (2.3) did 26 8 miles, but in traffic, so much torque you didn't need to rev, just lift clutch!! (29/30) if you remove the back box and fit a stright through pipe, no noiser but better response), and 760 turbo auto did 25.....37 down the M6.

On balance I'd say 25 is a bit stingy for a 416, but by what you're saying it sounds like all is well engine management wise. As an experiment, and this should in theory have no difference I know, but try a tank of higher octane petrol..... some cars (those meant to run on 95 NOT 97!) seem to do a few mpg's better, even though it should make no difference!! (if the min octane is 95, in theory using anyting more than 95 should yield no benefit, or so I understand)

If anybody can explain, please feel free...

CAM
 
#20 ·
CAM4V said:
Does it get up to heat quick enough? I'm thinking thermostat if it doesn't, that could be a possible explanation. To be honest I had a 1999 416i 2 weeks ago as a courtesy car, and it was a bit of a drinker too.

My 420 did 25 in winter, 28/30 Summer, on a 7 mile journey to work, and back. my 414 Sli never ever ever did anything less that 35, (same journey) my Volvo 740 (2.3) did 26 8 miles, but in traffic, so much torque you didn't need to rev, just lift clutch!! (29/30) if you remove the back box and fit a stright through pipe, no noiser but better response), and 760 turbo auto did 25.....37 down the M6.

On balance I'd say 25 is a bit stingy for a 416, but by what you're saying it sounds like all is well engine management wise. As an experiment, and this should in theory have no difference I know, but try a tank of higher octane petrol..... some cars (those meant to run on 95 NOT 97!) seem to do a few mpg's better, even though it should make no difference!! (if the min octane is 95, in theory using anyting more than 95 should yield no benefit, or so I understand)

If anybody can explain, please feel free...

CAM
Thanks very much, I think ive done a test as took it on a good run last week and got 33 mpg out of it, so much better, think it is the cold weather and also the short journeys I do, The car heats up normally I would say, within 5/10 mins it is 1/2 way, were it usually remains unless im on a real long drive were it goes up slightly, but it is usually warm. Thanks again but as said think it is all ok, just me worring a bi tlast week, now ive given it the run an got 33 out of it, im much more pleased. It seems to be dropping around 26/27 again at moment but thats because im on the short distance driving again - Steve :)
 
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