MPG Needle...What's the point?

JonMad · 02-22-2006, 12:33 PM

It's strange that the OBC doesn't have an instantaneous mpg function, even with the one on the dash. IIRC my old 540 had both.

It seems to be more of an 'inverse to where your foot is on the accelerator' gauge, rather than a mpg gauge. e.g. if you are idling or even if you are doing 6000rpm (4500rpm in my case) the needle says infinite mpg if your foot is off the gas, which can't be the case.

Saying that, with cruise control on (or a steady right foot) is does give a nice indication of your current incline and the effect that has on mpg.

(aside: I find the OBC average mpg is about 1.5mpg optimistic over time, due to the same reasons as above - whenever your foot is off the gas it thinks you're doing infinite mpg, so this will build up an error)

My $0.02
Jon

shragon · 02-22-2006, 12:40 PM

my old e34 had it, and i never used it. i found it to be a useless gauge. now it's on my e90, guess what, it's ignored again. i rather see something more useful, like a temp gauge in its place.

ward · 02-22-2006, 02:55 PM

Quote:

Originally Posted by bmq

I can respect tradition when it comes to family and Thanksgiving dinner, but just because it has always been there is not a good enough reason to keep it intact. If something has outgrown its usefulness, it should be replaced by something more appropriate....

so you think it was usefull once but not anymore??

anyone who thinks a temp gauge would be any more "usefull" lacks the understanding on what actual info (or more accurately, lack of info) a modern BMW temp gauge give you

vladinecko · 02-22-2006, 03:10 PM

Quote:

Originally Posted by JonMad

(aside: I find the OBC average mpg is about 1.5mpg optimistic over time, due to the same reasons as above - whenever your foot is off the gas it thinks you're doing infinite mpg, so this will build up an error)

i highly doubt they put "infinite" in the equation when they were creating this function. just because the needle goes off limits doesn't mean the car doesn't read the actual value of mpg. it's like saying that if you floor it, the car uses infinite amount of gas.

SRT · 02-22-2006, 03:12 PM

I suppose it is just an indication of how economical your driving-
I find it can be especially useful when on cruise control. Sometimes if I reach an incline, the MPG will move away from around 50 MPG to 35 MPG as the car tries to sustain it's speed - if there is no car behind, I just interrupt the cruise control till I get to the top of the inclination, gently feather the throttle to build up speed on the flat/downhill and back to cruise, and the MPG needle stays over 50

Another use is with gears. Sometimes the highest gear is not always the most economical (depends on speed of vehicle) and as you get used to your car, the MPG dial will allow you to understand what gear to be in at various speeds for maximum efficiency. On the whole it's just nice to know when your car is achieving it's highest MPG, rather than no immediate indication of economy.

bmq · 02-22-2006, 03:13 PM

Quote:

Originally Posted by ward

so you think it was usefull once but not anymore??

anyone who thinks a temp gauge would be any more "usefull" lacks the understanding on what actual info (or more accurately, lack of info) a modern BMW temp gauge give you

I don't think that the mpg needle was ever useful. It is a nice statistic to have as part of the over all engine monitors, but not as one of three or four "in-your-face" gauges.

And just because I think that the mpg gauge is gimmicky/useless, does not mean I automatically want it to be replaced by a temp gauge. There has to be a third option that is more useful for everyday driving.

ward · 02-22-2006, 03:28 PM

I will say, I liked the gauge better when it sat at zero MPG when idling rather than infinite.

sully · 02-22-2006, 06:06 PM

This gauge seems to be based purely on vacume in the intake tract,
hence the reason it says 50 when idling and zero when the gas pedal is smashed to the floor. I also own a Chevy Tahoe with a instant and average MPG gauge, when idling it says 0 mpg instead of 50 like the E90. That leads me to believe the BMW gauge is based only on vacume and nothing else, and the tahoe has some other influence other than just vacume. Personally i love this gauge in the E90 !!!

ex-poster · 02-22-2006, 06:16 PM

Boy, I'm really surprised no one knows the legacy of this gauge... Now, this is all from memory so don't quote me, but in the 70s after the first gas crisis, the EPA (DoE? Sorry...) was all over car manufacturers over gas mileage. This is when CAFE was born.

BMW wanted - in some way - credit for having an MPG gauge right in front of the driver. There was a fairly big fight over this, and I couldn't even tell you if BMW won or not, but that guage has been there ever since. Someone on the board should remember the gory details. (Note, no, I'm not that old, this is just something that's stuck in my mind ever since I heard about it)

With the Greens influence in Germany, I wouldn't think it's going away any time soon.

I'm off to Google this a bit and see if I can find some references.

I too like the MPG gauge.

tctic · 02-22-2006, 06:50 PM

Quote:

Originally Posted by JonMad

It's strange that the OBC doesn't have an instantaneous mpg function, even with the one on the dash. IIRC my old 540 had both.
Jon

You can get a reading off the OBC under the hidden OBC menu. In addition to L/100km (metric, not sure what the US cars does), it tells you L/hr as well.

tctic · 02-22-2006, 06:50 PM

Quote:

Originally Posted by ward

I will say, I liked the gauge better when it sat at zero MPG when idling rather than infinite.

Well.. if you live in a metric country, your fuel consumption gauge would rest at zero when idling.

ward · 02-22-2006, 06:55 PM

Quote:

Originally Posted by tctic

Well.. if you live in a metric country, your fuel consumption gauge would rest at zero when idling.

it's amazing the stupid little things they do to make americans think we're getting better gas mileage

Buick had a digital fuel gauge (read in gallons remaining) and they were getting major complaints from owners about poor fuel economy. They changed the calibration so that instead of reading 16 gallons (down from 17) just a few blocks from the station, the gauge skipped 16 and went straight from 17 to 15 gallons remaining and whammo, complaints dried up really quickly

Nikki · 02-22-2006, 07:05 PM

Why do any of you guys wnat a temperature gauge? It would just move like the mpg gauge and it doesn't tell you anything. The computer will display something if the car is overheating, so what else is the temperature guage for?

flipmde786 · 02-22-2006, 07:14 PM

The MPG gauge is there to make you think you have a boost gauge

DTM · 02-22-2006, 08:20 PM

From my experience, the MPG gauge tells you how heavy your foot is. It's like a bathroom scale, except only for your foot.

RedStripe · 02-22-2006, 10:02 PM

I use the mpg guage pretty much every time I drive. I wouldn't want it any other way!

poldim · 02-22-2006, 11:31 PM

Quote:

Originally Posted by Nikki

Why do any of you guys wnat a temperature gauge? It would just move like the mpg gauge and it doesn't tell you anything. The computer will display something if the car is overheating, so what else is the temperature guage for?

You have no way of telling when the car is warm while driving.

M3ti Compact · 02-22-2006, 11:41 PM

The car doesn't really need a temp gauge- it could make due with an idiot light which lights up when the car is cold and goes out when it's ready to floor.

OR they could have put in a variable redline like the M cars

And about the L/100kms gauge, it's quite useful. Fuel consumption is a big concern in this car- just look at the number of readouts that the car has that have to do with fuel.

Nikki · 02-22-2006, 11:42 PM

Quote:

Originally Posted by poldim

You have no way of telling when the car is warm while driving.

yeah, but why does it matter? if it's not warm enough for heat the auto setting won't blow until the car warms up, and if the car is too hot or too cold then a message would be displayed. what else do you need to know the temperature for? i thought the car heats up almost instantly anyways with the new technology.

poldim · 02-22-2006, 11:44 PM

Maybe my car is a lemon. If I had it on the highest setting before i left the car, when I get back in, it takes about 10 seconds for it to get upto full blast. This is with both set to 84 degrees, meanwhile blowing 30 degree air.
I'd also like to know that the engine is warm before I go flooring it. If you do it before its fully warmed up you cause a lot more damage.

Nikki · 02-22-2006, 11:52 PM

Well if it's 70-80 outside does your car still need to warm up? I never considered this really since I moved down here.

Thavash · 02-23-2006, 12:06 AM

I'm sorry I disagree with most people here. The MPG guage is extremely useful if you know how to use it to check the load on your engine. I would rather have it than a temperature guage. While I do drive my BMW enthusiastically, sometimes I try and get good fuel economy. On sunday morning I drove to the Airport ( R21 ) and the road was empty, and once up to speed I was cruising at 140-150. By checking the "Energy Control" while driving , it helped me do an average of about 7.0 l/100 km for that trip which is quite good for a petrol ( don't know what that is in MPG )

02-22-2006, 12:33 PM	#45
JonMad Second Lieutenant 6 Rep 235 Posts Drives: 320d SE;Mazda MX-5 Join Date: Oct 2005 Location: Hampshire, UK iTrader: (0) Garage List 1990 Mazda MX-5 [0.00] 2005 BMW 320d [0.00]	It's strange that the OBC doesn't have an instantaneous mpg function, even with the one on the dash. IIRC my old 540 had both. It seems to be more of an 'inverse to where your foot is on the accelerator' gauge, rather than a mpg gauge. e.g. if you are idling or even if you are doing 6000rpm (4500rpm in my case) the needle says infinite mpg if your foot is off the gas, which can't be the case. Saying that, with cruise control on (or a steady right foot) is does give a nice indication of your current incline and the effect that has on mpg. (aside: I find the OBC average mpg is about 1.5mpg optimistic over time, due to the same reasons as above - whenever your foot is off the gas it thinks you're doing infinite mpg, so this will build up an error) My $0.02 Jon
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02-22-2006, 12:40 PM	#46
shragon Moderator 497 Rep 27,441 Posts Drives: BMW Join Date: Oct 2005 Location: Bay Area, CA iTrader: (7)	my old e34 had it, and i never used it. i found it to be a useless gauge. now it's on my e90, guess what, it's ignored again. i rather see something more useful, like a temp gauge in its place. __________________ www.cardomain.com/id/shragon
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02-22-2006, 03:12 PM	#49
SRT Second Lieutenant 8 Rep 297 Posts Drives: BMW 5 Series Join Date: Sep 2005 Location: London, UK iTrader: (0)	I suppose it is just an indication of how economical your driving- I find it can be especially useful when on cruise control. Sometimes if I reach an incline, the MPG will move away from around 50 MPG to 35 MPG as the car tries to sustain it's speed - if there is no car behind, I just interrupt the cruise control till I get to the top of the inclination, gently feather the throttle to build up speed on the flat/downhill and back to cruise, and the MPG needle stays over 50 Another use is with gears. Sometimes the highest gear is not always the most economical (depends on speed of vehicle) and as you get used to your car, the MPG dial will allow you to understand what gear to be in at various speeds for maximum efficiency. On the whole it's just nice to know when your car is achieving it's highest MPG, rather than no immediate indication of economy.
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02-22-2006, 03:28 PM	#51
ward Major General 155 Rep 6,158 Posts Drives: F Join Date: May 2005 Location: T iTrader: (0)	I will say, I liked the gauge better when it sat at zero MPG when idling rather than infinite.
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02-22-2006, 06:06 PM	#52
sully Thats crazy talk 2 Rep 14 Posts Drives: 06" E90 325i Join Date: Jan 2006 Location: So Cal iTrader: (0) Garage List 2006 E90 325i [0.00]	MPG meter This gauge seems to be based purely on vacume in the intake tract, hence the reason it says 50 when idling and zero when the gas pedal is smashed to the floor. I also own a Chevy Tahoe with a instant and average MPG gauge, when idling it says 0 mpg instead of 50 like the E90. That leads me to believe the BMW gauge is based only on vacume and nothing else, and the tahoe has some other influence other than just vacume. Personally i love this gauge in the E90 !!!
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02-22-2006, 06:16 PM	#53
ex-poster Lieutenant 19 Rep 482 Posts Drives: 2000 328, 2006 330 Join Date: Jul 2005 Location: Chicago Burbs iTrader: (0)	Boy, I'm really surprised no one knows the legacy of this gauge... Now, this is all from memory so don't quote me, but in the 70s after the first gas crisis, the EPA (DoE? Sorry...) was all over car manufacturers over gas mileage. This is when CAFE was born. BMW wanted - in some way - credit for having an MPG gauge right in front of the driver. There was a fairly big fight over this, and I couldn't even tell you if BMW won or not, but that guage has been there ever since. Someone on the board should remember the gory details. (Note, no, I'm not that old, this is just something that's stuck in my mind ever since I heard about it) With the Greens influence in Germany, I wouldn't think it's going away any time soon. I'm off to Google this a bit and see if I can find some references. I too like the MPG gauge.
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02-22-2006, 07:05 PM	#57
Nikki Major General 990 Rep 6,381 Posts Drives: Sepang Z4MC Join Date: Aug 2005 Location: LA iTrader: (9)	Why do any of you guys wnat a temperature gauge? It would just move like the mpg gauge and it doesn't tell you anything. The computer will display something if the car is overheating, so what else is the temperature guage for? __________________ Nikki
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02-22-2006, 07:14 PM	#58
flipmde786 Lieutenant 25 Rep 513 Posts Drives: 330xi Join Date: Nov 2005 Location: Long Island, NY iTrader: (0)	The MPG gauge is there to make you think you have a boost gauge __________________ 2006 330xi [TiAg] [Black Leather] [Aluminum] [STEP] [ZPP] [ZSP] [ZCW] [CA] [35% tint] [Blacklines] [OEM Strut Bar] [OEM Spoiler]
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02-22-2006, 08:20 PM	#59
DTM Private First Class 23 Rep 151 Posts Drives: Accord Join Date: Jan 2006 Location: Massachusetts iTrader: (0)	From my experience, the MPG gauge tells you how heavy your foot is. It's like a bathroom scale, except only for your foot.
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02-22-2006, 10:02 PM	#60
RedStripe Captain 96 Rep 649 Posts Drives: 2006 BMW 325i Join Date: May 2005 Location: Texas iTrader: (1) Garage List 2006 BMW 325i [0.00]	I use the mpg guage pretty much every time I drive. I wouldn't want it any other way!
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02-22-2006, 11:41 PM	#62
M3ti Compact Private First Class 8 Rep 106 Posts Drives: E36 318ti, E90 325i Join Date: Feb 2006 Location: Toronto iTrader: (0) Garage List 1995 BMW 318ti [0.00] 2006 BMW 325 [0.00]	The car doesn't really need a temp gauge- it could make due with an idiot light which lights up when the car is cold and goes out when it's ready to floor. OR they could have put in a variable redline like the M cars And about the L/100kms gauge, it's quite useful. Fuel consumption is a big concern in this car- just look at the number of readouts that the car has that have to do with fuel.
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02-22-2006, 11:44 PM	#64
poldim Vroom Vrrooooom 300 Rep 3,146 Posts Drives: 330i Join Date: Oct 2005 Location: Bay Area, CA iTrader: (2) Garage List 2006 330i Sedan [0.00] 2003 GSX-R 600 [0.00]	Maybe my car is a lemon. If I had it on the highest setting before i left the car, when I get back in, it takes about 10 seconds for it to get upto full blast. This is with both set to 84 degrees, meanwhile blowing 30 degree air. I'd also like to know that the engine is warm before I go flooring it. If you do it before its fully warmed up you cause a lot more damage. __________________ -Dmitriy 06' BMW 330i & 03' Suzuki GSX-R600 SG \| Beige Dakota \| Poplar \|\| iDrive w/MP3 \| PP \| SP \| CWP \| PDC \| Comfort \| Shades \|\| 40% Tint \| Black Line Tail Lights \| Hardwired V1
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02-22-2006, 11:52 PM	#65
Nikki Major General 990 Rep 6,381 Posts Drives: Sepang Z4MC Join Date: Aug 2005 Location: LA iTrader: (9)	Well if it's 70-80 outside does your car still need to warm up? I never considered this really since I moved down here. __________________ Nikki
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02-23-2006, 12:06 AM	#66
Thavash Private First Class 20 Rep 166 Posts Drives: F30 M-Sport 320i Red Join Date: May 2005 Location: Johannesburg, South Africa iTrader: (0) Garage List 2018 BMW 320M [0.00] 2005 320i [0.00]	I'm sorry I disagree with most people here. The MPG guage is extremely useful if you know how to use it to check the load on your engine. I would rather have it than a temperature guage. While I do drive my BMW enthusiastically, sometimes I try and get good fuel economy. On sunday morning I drove to the Airport ( R21 ) and the road was empty, and once up to speed I was cruising at 140-150. By checking the "Energy Control" while driving , it helped me do an average of about 7.0 l/100 km for that trip which is quite good for a petrol ( don't know what that is in MPG )
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