z4 35i fuel consumption

S

sachak

Member
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.
 
... 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
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... is poor consumption. :?

My 35is gives the same figures, but in miles, not kilometres.
 
Mine usually gives about 400km (250 miles) before the fuel warning light comes on, and it's never driven 'granny-style' :D
 
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: )
 
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
 
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?
 
sachak said:
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?
Click to expand...

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...
AC20460B-DCD4-48F8-90DE-B69296F5D8F8.jpeg
Rob
 
Busterboo said:
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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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.
 
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.
 
Poor fuel consumption could be bad injectors or lambda sensors.

How old is your car and has it ever had injectors changed?

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

Take it to a good indy or BMW.
Click to expand...

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.
 
R.E92 said:
Poor fuel consumption could be bad injectors or lambda sensors.

How old is your car and has it ever had injectors changed?

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

Take it to a good indy or BMW.
Click to expand...

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.
Click to expand...

Don’t you mean removing the inlet manifold rather than the valve cover? :?
Rob
 
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....
 
R.E92 said:
Busterboo said:
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
Click to expand...

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.
Click to expand...

I understand how it works, but doubt that it will work in the way the OP wants.
 
As I've posted elsewhere, I use my 35is for fun and plenty of it. So, I've done 16,000 non-commuting miles in the last year. These have included quite a lot of short-burst, high-speed/fast-acceleration driving, but little long-distance.

The 35is's fuel consumption has, however, remained remarkably consistent. Push it as hard as I like, and I do, it still does about 295 on a tank of 95RON: 25.4mpg.

So, the OP's figures suggest he's losing quite a lot of something somewhere and removing carbon deposits ain't going to make enough difference.
 
Busterboo said:
R.E92 said:
Busterboo said:
Snake oil ain't going to give you a 20% 'correction' of your fuel consumption.

Take it to a good indy or BMW.
Click to expand...

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.
Click to expand...

I understand how it works, but doubt that it will work in the way the OP wants.
Click to expand...

Then you mis-used the term "snake oil".

Coked intake ports cause loss of power and misfires. Increased fuel consumption is also noticed.
 
Smartbear said:
R.E92 said:
Poor fuel consumption could be bad injectors or lambda sensors.

How old is your car and has it ever had injectors changed?

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

Take it to a good indy or BMW.
Click to expand...

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.
Click to expand...

Don’t you mean removing the inlet manifold rather than the valve cover? :?
Rob
Click to expand...

Yes, my mistake.
 
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