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KB8vsMJ23
02-02-2007, 01:42 AM
Since about a week ago my x3 3.0 has been getting horrible gas mileage. It's hovering around 13-14 with a mix of highway and local driving. I've tried STP cleaners but it hasn't been working, anyone got any suggestions??

AzNMpower32
02-02-2007, 06:45 AM
Do a search, it's been discussed before. Let the car break-in for another 10,000+ miles before reaching much better fuel efficiency.

dug01
02-02-2007, 07:00 AM
Since about a week ago my x3 3.0 has been getting horrible gas mileage. It's hovering around 13-14 with a mix of highway and local driving. I've tried STP cleaners but it hasn't been working, anyone got any suggestions??
What year and engine?? I have a '07 and am getting the EPA mileage--on a recent 3000 mile trip easily 25-27MPG and 18-19 in the suburbs in the cold weather. I know the older 3.0 with 5sp auto gets less than the '07 but not that different. Have the dealer do a diagnostic on it--covered by warranty. Also gas with ethanol added will reduce mileage--It has been documented that 10% ethanol will cause 5% drop in mileage--many add more ethanol during winter to prevent icing--also found that E85(85% ethanol) will drop mileage by 30 to 40%--
I don't understand how this helps our dependence on oil if we have to use more..:dunno:

judybe83
02-02-2007, 09:57 AM
Your problem could be anything from a clogged air filter to clogged catalytic converter and everything in between.

STP is NOT one of the better injector cleaners (but it is cheep) visit your favorite auto supply for some real injector cleaner, it will be 2 or 3 times the price of the STP.

ab

UncleJ
02-02-2007, 10:07 AM
That certainly doesn't sound like everything is working right. I suggest filling up the car driving 100 miles then filling it up again at the same pump if possible. Check your milage the old fashioned way and then you will have a good solid bench mark to discuss with your service mgr. During this time try to drive like you were on an economy run. I have an 06 and match dug01's milage so the car running right should do much better than you are experiencing, unless of course you have your foot into the firewall!

kjboyd
02-02-2007, 10:49 AM
I've been getting 12.8 consistently in mine since i had it. July 1. i have just under 5,000 miles. and no lead foot at all.

KB8vsMJ23
02-02-2007, 11:33 AM
Thanks for the replies guys, it's a 2004 and I just got it back from the dealer today for the check up. They said the diagnostic didn't turn up anything so I guess I'll have to wait till this tank is empty and try some other cleaners. It has 40k miles so the break in is definately not the issue. I really think it was some bad fuel, it was consistantly at around 19-20 with a mix of highway/local ever since I got the car new but all of a sudden it dropped after filling up. I'll keep everyone posted, more suggestions welcome. Thanks everyone.

Techson
02-02-2007, 12:46 PM
My 05 mileage blows... I've averaged just over 15 for the life of the X3 (21 months). That has included some highway driving and a lot of sport mode driving, but it still should be better. Good luck finding a solution.

Sonoman707
02-02-2007, 01:21 PM
Thanks for the replies guys, it's a 2004 and I just got it back from the dealer today for the check up. They said the diagnostic didn't turn up anything so I guess I'll have to wait till this tank is empty and try some other cleaners. It has 40k miles so the break in is definately not the issue. I really think it was some bad fuel, it was consistantly at around 19-20 with a mix of highway/local ever since I got the car new but all of a sudden it dropped after filling up. I'll keep everyone posted, more suggestions welcome. Thanks everyone.


When my '04 had around 39K - it had a drop in MPG. I mentioned it on a service visit - but they said the diagnostics didn't show anything. I was down to approx. 15 - 16 MPG on a weeks driving (very consistent every week - same mix of city/hwy/stop & go/etc.)

Eventually - it popped a SES light. http://www.bimmerfest.com/forums/showthread.php?t=184471 Took it in and they diagnosed a faulty oxygen sensor which was replaced. During the same visit, they also reprogrammed the DME.

Acceleration and shifting are noticeably improved and I am back up to the 20 - 21 MPG mark for my driving week (which had been the norm).

T

davelv
02-02-2007, 01:36 PM
Maybe you put in E85? This would get only 12 mpg, but more dangerously can really damage the whole fuel system.

AzNMpower32
02-02-2007, 03:20 PM
Maybe you put in E85? This would get only 12 mpg, but more dangerously can really damage the whole fuel system.
I don't think the engine will run on E85, and I seriously hope no one on this board is dumb enough to put it in regularly.

falou
02-04-2007, 12:51 AM
The first four tanks in my 07 I averaged 13.2, mostly city driving. Avg speed was 16mph, so pretty difficult to get any kind of mileage at that speed. I took one road trip and got about 20, but there was some city driving mixed in.