120d worrying fuel economy

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Manufactured from 2004 to 2013

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shaqs77
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120d worrying fuel economy

Post by shaqs77 » Tue Nov 28, 2017 4:28 am

hi guys

about two months ago I bought the mrs a 57 plate 120d m sport, 174bhp. im a bit surprised but the amount of miles im getting from a full tank. before this she owned a 2003 vw golf gttdi 150bhp. filled up to the brim and doing city driving I could easily hit between 500 - 525 miles out of a full tank.

I am getting approximately 260 miles out of a full tank which is filled with v power diesel. the alarming thing for me is that its ever so slightly better on fuel than my 300bhp Subaru impreza on which I get about 240 miles.

the 120d ive bought has got full dealer history from new and the car is mint and looks well looked after. what could be causing this issue??



cheers
2007 E87 120d m sport
2003 Impreza sti type uk

FirBim
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Re: 120d worrying fuel economy

Post by FirBim » Tue Nov 28, 2017 8:09 am

Thermostat fail, or maybe binding caliper? Fuel return lines leaking?
2010 E87 120d M Sport, Le Mans Blue

OneTwenty
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Re: 120d worrying fuel economy

Post by OneTwenty » Tue Nov 28, 2017 8:59 am

They have a small tank don't forget, so you need to look at miles vs cost rather than miles per tank.

Also depends what type of driving you do. My old E81 120d was rubbish on fuel in winter as I did mainly town driving, probably 32mpg average. My wife E91 does about 44 average over the year but that's with my Mrs driving slowly.
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OneTwenty
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Re: 120d worrying fuel economy

Post by OneTwenty » Tue Nov 28, 2017 8:59 am

Also as FirBim says, they are bad for binding callipers, mine had that which did affect MPG.
66 M240i Coupe, MW, Coral, Auto, Vis/Comfort/Sun, Pro Nav, Heated Wheel/Seats, Elec Seats/Lumbar, Adaptive, Camera/Park Assist, Speed Lim, HK, Split/Fold, WiFi/EBT, F/M

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THETYRANT
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Re: 120d worrying fuel economy

Post by THETYRANT » Tue Nov 28, 2017 9:21 am

As mentioned they have differnt size tanks so you need to look at the actual mpg not how miles to a tank etc, unless you make note of the amount of fuel its used when filling back up, the bmw diesel 4cylinder engine in 120d etc are not great in my opinion for anything other than long motorway cruises, petrols often just as good for shorter journeys so while there could be something wrong with your car as suggested it could just be normal depending on cars usage and actual mpg acheived.

The VW 1.9 GtTdi diesel engine you had in previous car is in my opinion one of best 4 cylinder diesel engines every made, my mate has had a few and always averaged 50mpg easy even with some thrashing about and city use, he changed to an E81 123d and engine and economy was awful in comparision, 123 was much nicer car of course but golf had better engine imo
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stevesurrey
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Re: 120d worrying fuel economy

Post by stevesurrey » Tue Nov 28, 2017 12:31 pm

Id say something is definitely wrong. Most of my driving is in the outer london suburbs yet still achieve around 40mpg, and get 50mpg or more when I get some longer runs too.Are the tyres inflated correctly ? How short are the journeys and what average speed does the OBC show ? Definitely worth checking the engines reaching proper temperature too as thermostat failure is relatively common judging by the number of incidents on this forum.
E81 120D (N47) SE+Dynamic Package, 2007/57, M Sports Suspension, Montego Blue, Pro HU+HiFi Speakers & Dipstick

shaqs77
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Re: 120d worrying fuel economy

Post by shaqs77 » Sun Dec 10, 2017 10:18 pm

i thought id check it again and im right. there is something wrong.

since the original post ive filled her up twice to the brim. filled it up when the fuel warning light came on. filled with shell v power diesel at all times. the best ive got is 260 miles. the scary thing is im getting 250 miles out of my impreza sti 300bhp. I cant check temps as there is no temp gauge.

Is there anything I could check before I book it in with sytners and get bent over
2007 E87 120d m sport
2003 Impreza sti type uk

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marco_polo
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Re: 120d worrying fuel economy

Post by marco_polo » Sun Dec 10, 2017 11:09 pm

There is a temp gauge, but it's hidden: Prior to attempting this you need to work out the code for your car. To do this simply add up the last 5 digits of your VIN. So if it ends in 12345 then 1+2+3+4+5 means your code is 15 and so on.

1. Insert key and start engine
2. Press and hold trip reset button in the corner of the dash for 10 seconds. Ignore the warnings that pop up.
3. You should be greeted by the last 7 of the cars vin on the dash
4. Press the trip reset button repeatedly to get menu 19 displayed, it should say 'lock on'

(if when you press the trip button it changes to 01.01 instead of 02.00, you will need to press and hold the trip button for 2 seconds to toggle to the L/H digits.)

5. After a couple of seconds the window will change to say code 00
6. Press the trip reset button repeatedly until your code is reached
7. After a couple more seconds it will take you back to step 01.00
8. Press the trip reset button till you reach test 07.00 which will display your coolant temp (KTMP MOM).

(after unlocking it, it might change to 01.01 instead of 02.00 again, so you may need to press and hold the trip button for 2 seconds to toggle to the L/H digits like before.)

To exit, switch off the engine. This will lock itself again though, so you need to unlock the rest of the menu steps again if you need the hidden menus.

N.B. if you have an Auto, 260 miles wouldn't be surprising. Auto's have a drinking problem.
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shaqs77
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Re: 120d worrying fuel economy

Post by shaqs77 » Mon Dec 11, 2017 12:01 am

Thanks. I’ll have ago. Why couldn’t they show us the info through the display normally?

It is an auto but I was expecting a lot better mileage than the tuned Impreza!!!!
2007 E87 120d m sport
2003 Impreza sti type uk

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stevesurrey
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Re: 120d worrying fuel economy

Post by stevesurrey » Mon Dec 11, 2017 11:52 am

Ahhhhh! you never mentioned it was an auto before!!
Better add that info to your signature.
E81 120D (N47) SE+Dynamic Package, 2007/57, M Sports Suspension, Montego Blue, Pro HU+HiFi Speakers & Dipstick

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