Anyone figured out how to adjust MPG reading?

0

04z4

Member
 North Alabama
I tired another forum about a week ago, but nobody was able to answer this, so I'll try again here:


My (minor) problem: the on-board computer in my 2004 Z4 reads about 10% high for the miles per gallon. I base this statement on the amount of fuel I put in when I fill up, versus the miles traveled, as reported by the odometer.

My question: has anyone figured out how to adjust/calibrate the system so that the MPG reading is more accurate? My Z3 had a "fudge factor" that you could bump up or down (took me years to find it) but I have not yet found something for the Z4.
 
Mines fairly accurate TBH. No idea how you would change it though, well calibrate it. You should not need to though, and if its 10% out then thats pretty bad.
 
On average mine under reads on 98ron and over estimates on 95ron

What i would say is the manual measuring isn't as accurate as you think if you use the stop-when-the-pump-clicks method. Different pumps are more/less sensitive, and it can even vary depending on how many pumps are in use on the forecourt at the time, what angle the nozzle it at, etc. It can easily be a litre or two variation.
 
As of this moment, apparently 144 people don't know the answer. I only need one person that does know the answer though :)

I'm still hoping the answer is out there somewhere, but perhaps it is not adjustable on the Z4. I thought maybe it was since the Z3 has a calibration factor.

And yes, even though I want my MPG computer to be more accurate, the 3.0 Z4 is definitely the car for me. Overall, I'm quite happy with the enjoyment/MPG ratio! (If I had no concern for fuel economy I would have surely bought an M.)
 
Did 600 miles this weekend to devon and back, over last 3 months ive been running on 97RON fuel i have noticed a little pattern emerging which i wondered would still hold true with 100% motorway journey.... Fill the tank to the brim, reset one of the MPG counters then readout when fuel empty 35MPG you get 350 miles to a tank, 30MPG gets you 300 miles, 37MPG gets you 370 ~ miles to the tank. I ignore the range as that is def a liar :-) But this seems to be pretty accurate!
 
yg54sg said:
Did 600 miles this weekend to devon and back, over last 3 months ive been running on 97RON fuel i have noticed a little pattern emerging which i wondered would still hold true with 100% motorway journey.... Fill the tank to the brim, reset one of the MPG counters then readout when fuel empty 35MPG you get 350 miles to a tank, 30MPG gets you 300 miles, 37MPG gets you 370 ~ miles to the tank. I ignore the range as that is def a liar :-) But this seems to be pretty accurate!
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Actually yeah, thats pretty close!
 
chrismann85 said:
10% is quite big, are you reading the imperial or US gallon? Is your car imported?
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US gallons. Car was not imported -- assembled right here in the good old US of A for the local market. :)

pilchardthecat said:
On average mine under reads on 98ron and over estimates on 95ron.
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The octane rating is something I never thought of but it makes perfect sense. Higher octane equals higher efficiency, to a point. In my case I have so far always put in 93 AKI which I think is equivalent to your 98 RON. Anyway, it is the highest octane that is readily available here without finding race fuel.

Sadly, right now all I can do is talk about my Z4, since it has been in the repair shop 1 week at the dealer, awaiting the installation of a replacement manual transmission in the remaining week of my CPO warranty (the problem was balky/inconsistent shifting). When I get it back and finally get to drive it again, my MPG will probably drop for at least a few days while I reacquaint myself with what I have been missing! :driving:
 
04z4 said:
As of this moment, apparently 144 people don't know the answer. I only need one person that does know the answer though :)

I'm still hoping the answer is out there somewhere, but perhaps it is not adjustable on the Z4. I thought maybe it was since the Z3 has a calibration factor.

And yes, even though I want my MPG computer to be more accurate, the 3.0 Z4 is definitely the car for me. Overall, I'm quite happy with the enjoyment/MPG ratio! (If I had no concern for fuel economy I would have surely bought an M.)
Click to expand...

I dont know why u guys on the other side of pond so worried about mpg as we pay a lot more for our fuel here anyway. £1.18/lt average now.
 
There is a slick IPhone app for tracking MPG called Road Trip. I track MPG not because of any concern about cost but to be aware of inconsistency in MPG which might be an indication of a problem.
 
nicko said:
chetalien said:
£1.18/lt average now.
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$7.08/US Gallon sounds worse
especially when the average in the US is about, what, $2.50 ?
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Premium is around $3.00 per gallon right now but it does vary from state to state due to different state tax amounts. My last fill up was $3.099 per gallon and that was for Shell V-Power.
 
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