z4 35i fuel consumption

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
sachak
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z4 35i fuel consumption

Post by sachak » Wed Jan 03, 2018 12:03 am

Hey all.

Would just like to know what you are all getting with regards to fuel consumption, I am not interested in what the computer has to say but rather in how many kilometers you are getting before the reserve light comes on.

I have driven my car for just over 6 months now and 3 of them have been modified and just over 3 months stock and my consumption hasn't really changed.

I am currently getting in the range of 250km - 290km to a tank with town driving, no traffic. just normal work and back town driving conditions with a bit of motorway here and there.

If I drive hard most days then I get around 250km to a tank. if I drive like an absolute granny and baby the throttle never allowing the car to boost then I get around 280 - 290km to a tank.

This to me is absolutely terrible consumption and would love to hear what you guys are getting and please just be honest about it, I need to know if this is normal or if something is wrong as I am getting no errors with my car according to MHD or Carly or the idrive.

All vacuum lines are brand new.
Spark plugs have less than 5k km on them,
Oil is brand new and you can see how I did my oil change in my previous thread.
Air filter is 3 months old.
Turbos have around 2 or 3k km on them as they are also brand new.

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z4 35i fuel consumption

Post by Busterboo » Wed Jan 03, 2018 12:15 am

... 250km - 290km to a tank with town driving, no traffic, just normal work and back town driving conditions with a bit of motorway here and there
... is poor consumption. :?

My 35is gives the same figures, but in miles, not kilometres.
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Steve S
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z4 35i fuel consumption

Post by Steve S » Wed Jan 03, 2018 12:20 am

Mine usually gives about 400km (250 miles) before the fuel warning light comes on, and it's never driven 'granny-style' :D
Last edited by Steve S on Wed Jan 03, 2018 12:30 am, edited 1 time in total.
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z4 35i fuel consumption

Post by Lazza » Wed Jan 03, 2018 12:25 am

Fuel light has just come on on mine and it’s at around 250 miles. And that’s probably the worst I’ve had so far (well there has been less traffic on the roads so I’ve used it “better” :driving: )
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z4 35i fuel consumption

Post by mr wilks » Wed Jan 03, 2018 12:28 am

The only time you can up the average to something decent is steady runs of 25/30 mile at 74/76mph . Recently covered 570 miles in one stint & average at the finish was 34mpg ( peak was 37.5mpg )
The UK miles of 320 were done between 50-74mph / the 250 French miles at 60-135 :oops:
Chugging around town or out in the lanes stop starting with no motorway use & mine soon settles around 23mpg :cry: give it throttle here & there then you can drop under 20mpg with little effort .
By comparison though ive just covered the same 570 miles in our C180 Kompressor & it struggled to break 36mpg & finished on 31mpg :cry: around town that sits at 24mpg :? the 35i is twin turbo 370bhp / the Merc is 1600cc supercharged with 170bhp so i'm more than happy with the N54 numbers
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sachak
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z4 35i fuel consumption

Post by sachak » Wed Jan 03, 2018 12:57 am

ok so it sounds like something is definitely wrong with the car.

Could this be due to a bad carbon build up around the valves? would a wall nut blasting remedy this problem?

What other things on these cars would typically cause this kind of bad consumption?

Busterboo
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z4 35i fuel consumption

Post by Busterboo » Wed Jan 03, 2018 1:49 am

Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
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z4 35i fuel consumption

Post by Smartbear » Wed Jan 03, 2018 2:14 am

sachak wrote:
Wed Jan 03, 2018 12:57 am
ok so it sounds like something is definitely wrong with the car.

Could this be due to a bad carbon build up around the valves? would a wall nut blasting remedy this problem?

What other things on these cars would typically cause this kind of bad consumption?
Hi, the biggest influence on mpg is driving style-I only have the 20i but you can see what’s possible with the right technique...
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e89 Sdrive3.0i this ones busted, pass me another...
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z4 35i fuel consumption

Post by sachak » Wed Jan 03, 2018 9:18 am

Busterboo wrote:
Wed Jan 03, 2018 1:49 am
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
I don't know what you mean by snake oil... :|

My car has been to bmw and other mechanics. No one has picked up anything. and to be perfectly honest I have had nothing but bad experiences with BMW.

@ Rob - Thanks for the driving tips, I have tried many different driving styles as I stated in my first post. and I have tried modded and stock. It always comes down to the same thing. Drive hard = 250km to a tank. Drive extremely efficiently and I get 280 - 290km to a tank.

Something in this car is causing excessive consumption and its not showing up on any computers as errors etc so I am just trying to find out what could cause high consumption on an N54.

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z4 35i fuel consumption

Post by benv6 » Wed Jan 03, 2018 10:30 am

Are you certain that your trip computer is set to km and not miles ?! Because 250 - 290 sounds about right but in miles not km.
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z4 35i fuel consumption

Post by R.E92 » Wed Jan 03, 2018 10:40 am

Poor fuel consumption could be bad injectors or lambda sensors.

How old is your car and has it ever had injectors changed?
Busterboo wrote:
Wed Jan 03, 2018 1:49 am
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
No snake oil involved with walnut blasting. You may be confusing it with other carbon cleaning procedures like seafoam.

Walnut blasting involves removing the valve cover and physically blasting the carbon deposits away. Fairly well established method of removing carbon deposits in direct injection engines.

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z4 35i fuel consumption

Post by Smartbear » Wed Jan 03, 2018 10:48 am

R.E92 wrote:
Wed Jan 03, 2018 10:40 am
Poor fuel consumption could be bad injectors or lambda sensors.

How old is your car and has it ever had injectors changed?
Busterboo wrote:
Wed Jan 03, 2018 1:49 am
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
No snake oil involved with walnut blasting. You may be confusing it with other carbon cleaning procedures like seafoam.

Walnut blasting involves removing the valve cover and physically blasting the carbon deposits away. Fairly well established method of removing carbon deposits in direct injection engines.
Don’t you mean removing the inlet manifold rather than the valve cover? :?
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e89 Sdrive2.0 18i, which has turned into a 20i :D
e89 Sdrive3.0i this ones busted, pass me another...
e85 3.0si, i sold my trouble free car...

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z4 35i fuel consumption

Post by Z4M-2006 » Wed Jan 03, 2018 11:07 am

My 35is was mapped and on a run i could just sneak 40mpg.....38 being achievable fairly easily.

24-25mpg on the daily commute..

Driving style is main factor on mpg....

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z4 35i fuel consumption

Post by Busterboo » Wed Jan 03, 2018 11:12 am

benv6 wrote:
Wed Jan 03, 2018 10:30 am
Are you certain that your trip computer is set to km and not miles ?! Because 250 - 290 sounds about right but in miles not km.
Clever.
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z4 35i fuel consumption

Post by Busterboo » Wed Jan 03, 2018 11:24 am

R.E92 wrote:
Wed Jan 03, 2018 10:40 am
Busterboo wrote:
Wed Jan 03, 2018 1:49 am
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
No snake oil involved with walnut blasting. You may be confusing it with other carbon cleaning procedures like seafoam.

Walnut blasting involves ... physically blasting the carbon deposits away. Fairly well established method of removing carbon deposits in direct injection engines.
I understand how it works, but doubt that it will work in the way the OP wants.
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