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Discussion Starter #1
have an 06 with cf/bmc/rpi/dinan exhaust and just had my software updated to the latest rev. My fuel economy has dropped quite a bit.

The dealer said the car has to re-learn my driving behavior/etc., but its been a few tanks of gas of "re-learning". It wouldn't be THAT bad if the car also felt like it was faster, but it doesn't. Is BMW richening the AF ratios to decrease HP and thus MPG or do I just need to be patient?

Thanks for your input!
 

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the 9.6mpg average is based on how many tanks/miles?
not sure if the dealer is giving you correct info... should probably ask them what version of the software you have...
can't imagine such a drastic change in air fuel mixture especially if you don't feel it in the butt dyno.
 

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My guess is when the updated the software, it reset the trip computer. This startes your average MPG all over again and asumes a starting point of 6 mpg. If your old average was over a long period of time, it may have included more higher mileage driving than your recent driving. Nothing to worry about. Your actual fuel efficiency likely has not changed at all. The dealer telling you that the car needs to re-learn your driving habits may be true for shifting, acceleration, etc., but has absolutely nothing to do with fuel economy.
 

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Discussion Starter #4
Hmm.. I was thinking the same Andrew, but I've had my car battery unplugged before where the mpg starts at 6 and then quickly normalizes to the 11'ish range. With the software revision it quickly normalized at 9.3ish and has only ticked up to 9.6mpg.

Further I thought the fuel economy was based only on the last 20 miles driven??
 

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I just had software updated to 28.02 and have similar results with the display, but I've gone up to the 10's now! I'm hoping it'll return to normal eventually. We also hand calculate every tank, so according to that, the "economy", or lack there of, is about the same as it was prior to the update.
 

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Further I thought the fuel economy was based only on the last 20 miles driven??
Don't know for sure, but I thought is was a much larger sample period.
 

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Fuel economy is not based on last 20 miles driven. It is total fuel consumption compared to total miles driven within your time reference. If you reset the computer, it starts at 0.0 MPG, but our computer defaults to 6.0 MPG as the lowest reading.

As far as fuel efficiency, I've never had a software update and have never reset my computer. MPG has been slowly climbing from 6.0 initially (brand new) to now 12.4 MPG. I assume that's a more accurate reading after logging 11,000 miles than to base what you see after a few tanks of gas.

Also to note, I've had my O2 sensor replaced, and during the time my A/F mixture was rich, I noticed no difference in fuel consumption nor any changes with the butt dyno experience.
 

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12.4 mpg seems about right.............9.3 is horrible. Even with only two tanks it should be better than that. Me thinks the computer needs a speed reading course. :dunno:
 

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Discussion Starter #10
I presume I got the absolute latest software release. Dealer said it had to update 200 modules and took over 3 hours to do the update fwiw.

How can I check on the car to see? Do the hidden menus show this?

I'd love 12.4mpg..
 

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I had the software update back in Nov 07, it had no effect on my mpg which has never varied moch more than 12.2 to 12.5 on the 4 E60 M5s I have owned. :dunno:
 

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...How can I check on the car to see? Do the hidden menus show this? ..
Just give them a call. I got reflashed last October and they told me my sw version 31, but according to this board, v.27 is the lastest. So, just curious.
 

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I just had the iPod intergration kit installed and I think they also loaded my car with the latest SW version when they programed the interface. My MPG was reading around 10.6 before the work was done and when I got it back, it was around 8.0 I think. It's slow back to 9.6 right now.

I think we should just go back to the old way of manually calculating our MPGs by resetting the trip meter and then dividing by total gallons pumped each time.

Also, my oil was reading .8L and it's now 1.0L after the iPod programming. That makes me worry cause I know they didn't do an oil change so I'm not sure what the actual oil volumne is.
 

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Have you checked the units your car is calculating, you may find that your car is now using US gallons and it was using Imperial gallons.

I think if you use the voice command
UNITS
you can change the units.
 

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I'll add that I would be amazed if anyone is doing 12.4 US mpg as that is 14.9 Imperial.

I'm sure your not all driving Miss Daisy.
 

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Latest SW version according to my dealer is 28.02. Just had it programmed last week (Mon/Tues).
 

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Discussion Starter #18
yeah.. the funny thing is.. Gas $3.30 a gallon. Organic Milk $6 a gallon. Driving to grocery store and back for a gallon of milk is a $10 exercise... lol.
 

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Am I missing something? You guys know you can hold down the BC button (while viewing the MPG) to force a reset of just the MPG counter, right? The counter probably just got reset when they put the new software in. I actually reset mine all the time to see how I did on a particular trip etc. No need to manually calculate this yourself using gas pumped in and miles driven when you can just hold the switch down and reset it.
 

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Am I missing something? You guys know you can hold down the BC button (while viewing the MPG) to force a reset of just the MPG counter, right? The counter probably just got reset when they put the new software in. I actually reset mine all the time to see how I did on a particular trip etc. No need to manually calculate this yourself using gas pumped in and miles driven when you can just hold the switch down and reset it.
+1 and +1 to AndrewSherman's post.

A lot has to do with when you reset vs. driving style. I find that if I reset while rolling down the freeway as opposed to stoped in traffic it will generally start higher and stay higher. This may make me feel better, but I am obviously not getting any better or worse gas mileage and I suspect you are not either. It is an average. I suspect that your average before the reset included more freeway miles or long trips and after the reset it might have even sat running at the dealer or putting around in stop and go traffic. It should average out eventually. Try resetting it when you are cruising on the freeway and then let it average out over your normal driving.

Wow I am averaging +14-mpg still since the last time I did this. I just can't keep it from creeping back towards the inevitable <10-mpg I see commuting around the yeah area.
 
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