Fuel Economy Inaccurately Reported on Trip Computer

Northern335i · 04-07-2011, 03:57 PM

My trip computer is extremely optimistic in displaying my MPG. It typically overstates the actual fuel economy by 5-6mpg. This also impacts the range calculation. I have a 2009 335i Auto. Do other people have this problem? Is it repairable? Thanks in advance!

RaceBlood · 04-07-2011, 04:02 PM

If you had a software upgrade or some other work done, you may need to reset it, I only know this from a conversation I heard in a shop a few days ago. Hopefully someone here can elaborate.

Northern335i · 04-07-2011, 04:05 PM

Tried that. No help whatsoever. This is definitely a long-term issue, immune to resets.

EVTee · 04-07-2011, 04:59 PM

I get better fuel economy than what the trip computer states. I reset my trip computer every time I fill up to see how close the estimate is to the real consumption.

sk8board511 · 04-07-2011, 06:16 PM

My MPG's are always within +/- 1 of the computer after a full tank calculation

bsamoul · 04-07-2011, 06:51 PM

Quote:

Originally Posted by sk8board511

My MPG's are always within +/- 1 of the computer after a full tank calculation

Same here, maybe 2.

Pinarello Rider · 04-07-2011, 06:55 PM

My computer overstated actual by .7mgp last time. 5-6mpg is HUGE and likely a problem.

I wonder how much of it is related to the speedometer garbage. My speedo says I'm going about 10% faster than I am really am. I used my boss's Tom Tom for a comparo, and sure enough, it was exactly what I suspected.

ww007 · 04-07-2011, 06:55 PM

Odd, mine typically overstates the actual mpg by about 0.5 to 1 mpg. 5-6 seems way out of line. Do you have iDrive?

John 070 · 04-07-2011, 06:57 PM

Crazy post....the mpg computer is not off by 5 mpg. Simply fill up the car, drive, fill it up again with the same pump. Subtract current odo by previous odo. Then divide by gals pumped. Compare to computer. I've done that for over 4 years, and it was never off by 0.2 mpg. Pretty statistically reliable and valid.

nbkkvv5 · 04-07-2011, 07:09 PM

My computer mpg is almost spot on compared to the old fashion way. For the 1st 6 months, I compared my mpg to the computer and it showed anywhere between .2 to .5 difference. Close enough for government work if you ask me.

5 to 6 mpg difference sounds like something is wrong with either:
1. The computer or
2. The way your doing manual calculations or
3. Gas pump is giving you less gas than your paying for

You can eliminate #3 if your buying gas from different stations and still getting the same mpg.

jgerv · 04-07-2011, 09:05 PM

Make sure you set your car language to US english and not UK english as they measure mpg differently... As US gallons are different size to UK gallons.

Northern335i · 04-07-2011, 09:32 PM

jgerv! I checked the computer and it was set to UK English. Changed it to US English and the stated consumption dropped from 29.7mpg to 24.5mpg. Which is exactly spot on. Thanks for saving me a trip to the dealer!

ctuna · 04-07-2011, 11:59 PM

about 1 mpg optomistic against manual calculations for me.

smokinHawk · 04-08-2011, 10:14 AM

i am hoping it is close to accurate (first tank for me) as I am getting about 28mpg.

04-07-2011, 03:57 PM	#1
Northern335i New Member 11 Rep 24 Posts Drives: 2019 330i xdrive sedan Join Date: Oct 2010 Location: Minneapolis iTrader: (0)	Fuel Economy Inaccurately Reported on Trip Computer My trip computer is extremely optimistic in displaying my MPG. It typically overstates the actual fuel economy by 5-6mpg. This also impacts the range calculation. I have a 2009 335i Auto. Do other people have this problem? Is it repairable? Thanks in advance!
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04-07-2011, 04:02 PM	#2
RaceBlood Going nowhere fast. 58 Rep 2,243 Posts Drives: 2 wheels Join Date: Mar 2011 Location: Downtown iTrader: (0)	If you had a software upgrade or some other work done, you may need to reset it, I only know this from a conversation I heard in a shop a few days ago. Hopefully someone here can elaborate.
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04-07-2011, 04:59 PM	#4
EVTee Second Lieutenant 65 Rep 267 Posts Drives: 2019 X3 M40i Join Date: Mar 2010 Location: Vancouver, BC iTrader: (0)	I get better fuel economy than what the trip computer states. I reset my trip computer every time I fill up to see how close the estimate is to the real consumption.
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04-07-2011, 06:16 PM	#5
sk8board511 Captain 48 Rep 689 Posts Drives: 07 E90-Bikes on bikes on bikes Join Date: Feb 2010 Location: Charlotte NC iTrader: (0)	My MPG's are always within +/- 1 of the computer after a full tank calculation __________________ KING"ish" OF Changed for collins
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04-07-2011, 06:55 PM	#7
Pinarello Rider Second Lieutenant 11 Rep 269 Posts Drives: 328i Sedan Join Date: Feb 2011 Location: Chesterfield, Virgineeee iTrader: (0)	My computer overstated actual by .7mgp last time. 5-6mpg is HUGE and likely a problem. I wonder how much of it is related to the speedometer garbage. My speedo says I'm going about 10% faster than I am really am. I used my boss's Tom Tom for a comparo, and sure enough, it was exactly what I suspected.
	Appreciate 0 Quote

04-07-2011, 04:05 PM	#3
Northern335i New Member 11 Rep 24 Posts Drives: 2019 330i xdrive sedan Join Date: Oct 2010 Location: Minneapolis iTrader: (0)	Tried that. No help whatsoever. This is definitely a long-term issue, immune to resets.
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04-07-2011, 06:55 PM	#8
ww007 Second Lieutenant 16 Rep 227 Posts Drives: 2011 e93 335i Join Date: Jan 2011 Location: Pasadena, CA iTrader: (0) Garage List 2011 BMW 335i e93 ' ... [0.00]	Odd, mine typically overstates the actual mpg by about 0.5 to 1 mpg. 5-6 seems way out of line. Do you have iDrive? __________________ 2011 335i e93 'vert 6-AT \| Le Mans Blue Metallic \| Coral Red \| Dark Glacier Aluminum trim Premium Package \| Convenience Package \| Cold Weather Package \| M-sport package w/ 18" alloy wheels and paddle shifters \| Navigation \| Harman Kardon \| iPod and USB adapter
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04-07-2011, 06:57 PM	#9
John 070 Lieutenant General 1725 Rep 14,825 Posts Drives: 335i cpe Join Date: Oct 2006 Location: ZSP/ZPP/ZCW iTrader: (0)	Crazy post....the mpg computer is not off by 5 mpg. Simply fill up the car, drive, fill it up again with the same pump. Subtract current odo by previous odo. Then divide by gals pumped. Compare to computer. I've done that for over 4 years, and it was never off by 0.2 mpg. Pretty statistically reliable and valid.
	Appreciate 0 Quote

04-07-2011, 07:09 PM	#10
nbkkvv5 Second Lieutenant 3 Rep 256 Posts Drives: 09 E90 335i Join Date: Nov 2009 Location: SF Bay Area iTrader: (0)	My computer mpg is almost spot on compared to the old fashion way. For the 1st 6 months, I compared my mpg to the computer and it showed anywhere between .2 to .5 difference. Close enough for government work if you ask me. 5 to 6 mpg difference sounds like something is wrong with either: 1. The computer or 2. The way your doing manual calculations or 3. Gas pump is giving you less gas than your paying for You can eliminate #3 if your buying gas from different stations and still getting the same mpg.
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04-07-2011, 09:05 PM	#11
jgerv boosted x 2 8 Rep 108 Posts Drives: 2007 BMW 335i Join Date: May 2010 Location: Winnipeg, Canada iTrader: (3)	Make sure you set your car language to US english and not UK english as they measure mpg differently... As US gallons are different size to UK gallons. __________________ 2007 TIAG 335i \|\| ZPP \|\| CA \|\| LOGIC 7 \|\| JB4 \|\| BMS DCI \|\| VMR V710 \|\| BMW PE EXHAUST \|\| M-TECH CF SPOILER \|\| BLACKLINES \|\| MTEC V3 AE \|\|
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04-07-2011, 09:32 PM	#12
Northern335i New Member 11 Rep 24 Posts Drives: 2019 330i xdrive sedan Join Date: Oct 2010 Location: Minneapolis iTrader: (0)	And the winner is... jgerv! I checked the computer and it was set to UK English. Changed it to US English and the stated consumption dropped from 29.7mpg to 24.5mpg. Which is exactly spot on. Thanks for saving me a trip to the dealer!
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04-07-2011, 11:59 PM	#13
ctuna Lieutenant General 2045 Rep 13,359 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	about 1 mpg optomistic about 1 mpg optomistic against manual calculations for me.
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04-08-2011, 10:14 AM	#14
smokinHawk 623lb puller 26 Rep 199 Posts Drives: 2017 340I XDrive MT Black Join Date: Mar 2011 Location: ohio iTrader: (2)	i am hoping it is close to accurate (first tank for me) as I am getting about 28mpg.
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