HELP

racingspice · 12-30-2023, 12:07 PM

Just bought a 2007 3.0si coupe with 51,000 miles and have put 50 miles on it so far. For some reason, my digital speedometer readout says I'm going 12.8 mph at a standstill. Anyone have any suggestions as to why that is?

I am also getting around 14 mpg from driving around the countryside in 50F weather. My battery voltages are 12.0V with engine off and 14.5V with engine on. I also checked my intake filter and it looked good. Im new to engines so any suggestions would be greatly appreciated. I also haven't pushed this car hard yet, so I shouldn't be getting this low of mpg. From my understanding, people are getting 20+ mpg without trying.

Best,
New member of the Z4 community

mlquillin · 12-30-2023, 12:36 PM

That readout is your average speed not current speed.

racingspice · 12-30-2023, 12:57 PM

Wow makes way more sense, thank you. How do you reset it if not with the trip odometer?

XMetal · 12-30-2023, 02:16 PM

Press and hold the button on the signaling stalk while the average miles per hour is being displayed

Huz-Z · 12-30-2023, 03:09 PM

The many mysteries of the E85/86 and their answers are revealed here:

https://cdn.dealereprocess.org/cdn/s...mw/2007-z4.pdf

racingspice · 12-30-2023, 04:09 PM

Great thanks guys. Any thoughts on the mpg?

XMetal · 12-30-2023, 05:05 PM

How are you measuring your mpg? Through the same gauge? If so, that's the average mpg since the last reset and you may want to reset it and monitor again.

wdb · 01-01-2024, 05:34 PM

Quote:

Originally Posted by XMetal

How are you measuring your mpg? Through the same gauge? If so, that's the average mpg since the last reset and you may want to reset it and monitor again.

Or:

fill the tank
take note of the odometer reading
drive 100 miles or more
fill the tank again
note the gallons required to fill
subtract the earlier odometer reading from the current odometer reading
divide the answer by the number of gallons
trip odometer may also be used to save maths

I know, I know, I must be old.

Jlo89 · 01-27-2024, 03:43 PM

If you don’t mind sharing, how much did you pay?

racingspice · 01-27-2024, 04:06 PM

About 16.5k!

Also a quick update. After putting 300 miles on the car, I'm now getting about 25 mpg combined. I think the battery was just low so the alternator was constantly on. Thanks everyone for the tips

12-30-2023, 12:07 PM	#1
racingspice New Member 5 Rep 6 Posts Drives: 2007 BMW Z4 3.0SI Join Date: Dec 2023 Location: Pennsylvania iTrader: (0)	HELP - Innacurate MPH and terrible MPG Just bought a 2007 3.0si coupe with 51,000 miles and have put 50 miles on it so far. For some reason, my digital speedometer readout says I'm going 12.8 mph at a standstill. Anyone have any suggestions as to why that is? I am also getting around 14 mpg from driving around the countryside in 50F weather. My battery voltages are 12.0V with engine off and 14.5V with engine on. I also checked my intake filter and it looked good. Im new to engines so any suggestions would be greatly appreciated. I also haven't pushed this car hard yet, so I shouldn't be getting this low of mpg. From my understanding, people are getting 20+ mpg without trying. Best, New member of the Z4 community Attached Images
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12-30-2023, 12:36 PM	#2
mlquillin New Member 5 Rep 13 Posts Drives: 2003 Z4 3.0i Convertible Join Date: Sep 2023 Location: Eugene, OR iTrader: (0) Garage List 2003 BMW Z4 3.0i [7.50]	That readout is your average speed not current speed.
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12-30-2023, 12:57 PM	#3
racingspice New Member 5 Rep 6 Posts Drives: 2007 BMW Z4 3.0SI Join Date: Dec 2023 Location: Pennsylvania iTrader: (0)	Wow makes way more sense, thank you. How do you reset it if not with the trip odometer?
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12-30-2023, 02:16 PM	#4
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Press and hold the button on the signaling stalk while the average miles per hour is being displayed __________________
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12-30-2023, 03:09 PM	#5
Huz-Z Brigadier General 851 Rep 4,057 Posts Drives: Z4 3.0si, 328 XDrive, X5 35i Join Date: Aug 2009 Location: Canada iTrader: (0)	The many mysteries of the E85/86 and their answers are revealed here: https://cdn.dealereprocess.org/cdn/s...mw/2007-z4.pdf
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12-30-2023, 04:09 PM	#6
racingspice New Member 5 Rep 6 Posts Drives: 2007 BMW Z4 3.0SI Join Date: Dec 2023 Location: Pennsylvania iTrader: (0)	Great thanks guys. Any thoughts on the mpg?
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12-30-2023, 05:05 PM	#7
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	How are you measuring your mpg? Through the same gauge? If so, that's the average mpg since the last reset and you may want to reset it and monitor again. __________________
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01-27-2024, 03:43 PM	#9
Jlo89 New Member 0 Rep 8 Posts Drives: BMW Z4 Join Date: Sep 2023 Location: Cali iTrader: (0)	If you don’t mind sharing, how much did you pay?
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01-27-2024, 04:06 PM	#10
racingspice New Member 5 Rep 6 Posts Drives: 2007 BMW Z4 3.0SI Join Date: Dec 2023 Location: Pennsylvania iTrader: (0)	About 16.5k! Also a quick update. After putting 300 miles on the car, I'm now getting about 25 mpg combined. I think the battery was just low so the alternator was constantly on. Thanks everyone for the tips
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