mpg readout

chrisbin · 07-26-2005, 05:54 AM

Can anyone explain this?

When travelling, in-gear, but no power applied, the readout will indicate maximum mpg - end of the scale. But if I knock it out of gear, so that the car is coasting, the readout comes down a couple of pegs.........

I would have expected the engine to be doing more when in gear than when its not....????

Is it because on "overrun" there is no fuel being supplied, whereas when coasting the engine is being supplied enough for it to tickover???

Not important, not a problem, just intriguing......

nexus66 · 07-26-2005, 06:20 AM

Yup - I've heard this before...

When you're on "overrun" the engine doesn't actually need any fuel, whereas when coasting it indeed needs fuel to tick-over! Hence why you shouldn't coast to a stop!

Do y'all think we can save the planet this way??

bobnaz · 07-26-2005, 07:58 AM

Quote:

Originally Posted by chrisbin

Can anyone explain this?

When travelling, in-gear, but no power applied, the readout will indicate maximum mpg - end of the scale. But if I knock it out of gear, so that the car is coasting, the readout comes down a couple of pegs.........

I would have expected the engine to be doing more when in gear than when its not....????

Is it because on "overrun" there is no fuel being supplied, whereas when coasting the engine is being supplied enough for it to tickover???

Not important, not a problem, just intriguing......

I believe it just an estimate as it is vacum controlled.

kronzprinz · 07-26-2005, 08:04 AM

don't pay attention to that needle, it'll drive you nuts

Broken1 · 07-26-2005, 10:03 AM

Does the UK use mpg??? I'm sure the Uk uses km's and liters which means your guage should be l/100kms?

xcalibr · 07-26-2005, 11:06 AM

i think someone said something about that being because when you're in gear, the engine is kept running by the wheels turning, but in neutral the engine needs to expend extra gas to stay idle-ing. do a search... there's a thread out there somewhere that explains it better than i can remember it.

crazybones · 07-26-2005, 12:11 PM

Quote:

Originally Posted by Broken1

Does the UK use mpg??? I'm sure the Uk uses km's and liters which means your guage should be l/100kms?

We use miles per gallon (English gallon), but we have to buy our petrol by the litre (to comply with Europe, I believe). My OBC can be switched between mpg & km/l

F32Fleet · 07-26-2005, 12:18 PM

Quote:

Originally Posted by bobnaz

I believe it just an estimate as it is vacum controlled.

you are correct and it's a good estimate.

skimo · 07-26-2005, 04:35 PM

Quote:

Originally Posted by nexus66

Yup - I've heard this before...

When you're on "overrun" the engine doesn't actually need any fuel, whereas when coasting it indeed needs fuel to tick-over! Hence why you shouldn't coast to a stop!

Do y'all think we can save the planet this way??

Wow...I have been coasting forever ! Thanks for the tip...

But I am still confused...if you are not coasting, then the engine is still in gear and you are basically doing a gear (or engine) break....? Doesnt that require more fuel then just coasting?

SKimo

LEDZEP · 07-26-2005, 04:43 PM

Quote:

Originally Posted by nexus66

Do y'all think we can save the planet this way??

Nah, what's the planet ever done for US?

skimo · 07-26-2005, 04:56 PM

Quote:

Originally Posted by LEDZEP

Nah, what's the planet ever done for US?

Look what the US has done to the planet.....

LEDZEP · 07-26-2005, 07:27 PM

Quote:

Originally Posted by skimo

Look what the US has done to the planet.....

Yeah, 'cause no other country has ever polluted or anything.

chrisbin · 07-27-2005, 04:53 AM

Quote:

Originally Posted by Broken1

Does the UK use mpg??? I'm sure the Uk uses km's and liters which means your guage should be l/100kms?

Errrrrr.......
"Chrisbin - location - S. Wales, UK"

"Broken1 - location - S.Africa"

Yes, we use mpg and measure distances in miles, and the speedo reads in mph, but we buy petrol in litres........

Well all the above was true this morning............

chrisbin · 07-27-2005, 04:56 AM

Quote:

Originally Posted by skimo

Wow...I have been coasting forever ! Thanks for the tip...

But I am still confused...if you are not coasting, then the engine is still in gear and you are basically doing a gear (or engine) break....? Doesnt that require more fuel then just coasting?

SKimo

Yep, that was my first thought. But as far as I understand it, on overrun/engine break, the engine isn't being fuelled whereas coasting its ticking over and using the appropriate amount of fuel....

Is that right???

David328M-Sport · 07-27-2005, 05:48 AM

from memory ], i remember reading that at least in previous bmw engines, the fuel automatically cuts out during engine braking.

not sure about the new ones, but i would hazzard a guess that it would be the same.

by the way, down under here in australia, we use the metric system so it's km/h, l/100km and i'm a gettin 17" wheels!!!!! heh, heh, heh.

saturday, here we come!!!!

chrisbin · 07-27-2005, 05:56 AM

Quote:

Originally Posted by David325Australia

from memory ],

by the way, down under here in australia, we use the metric system so it's km/h, l/100km and i'm a gettin 17" wheels!!!!! heh, heh, heh.

saturday, here we come!!!!

JVFan · 07-27-2005, 09:11 AM

Usually senseless add-ons are a domestic car thing....that fuel use needle has always made me wonder what the hell the point was...no one else, to my knowledge, needs to tell you that when you are accelerating you use more fuel than when you are decelerating....go figure.

chrisbin · 07-27-2005, 09:43 AM

Couldn't agree more......but they've been fitting them for ages now.....as have M-B.......

07-26-2005, 05:54 AM	#1
chrisbin Colonel 112 Rep 2,333 Posts Drives: 640i MSport Coupe Join Date: May 2005 Location: S.Wales, UK iTrader: (1)	mpg readout Can anyone explain this? When travelling, in-gear, but no power applied, the readout will indicate maximum mpg - end of the scale. But if I knock it out of gear, so that the car is coasting, the readout comes down a couple of pegs......... I would have expected the engine to be doing more when in gear than when its not....???? Is it because on "overrun" there is no fuel being supplied, whereas when coasting the engine is being supplied enough for it to tickover??? Not important, not a problem, just intriguing...... __________________ Current: F13 640i MSport, e85 Z4 3.0i Previous - Alpina D3 BiTurbo E90 LCI Manual, 320d M Sport E92 Auto, 330i M Sport E92 courtesy of BMW UK....320i M Sport E92 Auto, 320d SE E90 Manual.
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07-26-2005, 06:20 AM	#2
nexus66 Second Lieutenant 64 Rep 239 Posts Drives: F80 M3 Join Date: Apr 2005 Location: Scotland iTrader: (0)	Yup - I've heard this before... When you're on "overrun" the engine doesn't actually need any fuel, whereas when coasting it indeed needs fuel to tick-over! Hence why you shouldn't coast to a stop! Do y'all think we can save the planet this way??
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07-26-2005, 08:04 AM	#4
kronzprinz Second Lieutenant 7 Rep 286 Posts Drives: 2008 M3 Join Date: Jun 2005 Location: EASTCOAST iTrader: (0)	don't pay attention to that needle, it'll drive you nuts
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07-26-2005, 10:03 AM	#5
Broken1 Addict 203 Rep 2,074 Posts Drives: 2024 X5 40i M-Sport Join Date: May 2005 Location: Ontario iTrader: (0)	Does the UK use mpg??? I'm sure the Uk uses km's and liters which means your guage should be l/100kms?
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07-26-2005, 11:06 AM	#6
xcalibr First Lieutenant 18 Rep 370 Posts Drives: E90 325xi Join Date: Jun 2005 Location: Fremont, CA iTrader: (4) Garage List 2006 E90 325xi [0.00]	i think someone said something about that being because when you're in gear, the engine is kept running by the wheels turning, but in neutral the engine needs to expend extra gas to stay idle-ing. do a search... there's a thread out there somewhere that explains it better than i can remember it.
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07-27-2005, 05:48 AM	#15
David328M-Sport Brigadier General 101 Rep 3,566 Posts Drives: F30 M-Sport 328i Estoril Blue Join Date: Jun 2005 Location: Melbourne Australia iTrader: (0)	from memory ], i remember reading that at least in previous bmw engines, the fuel automatically cuts out during engine braking. not sure about the new ones, but i would hazzard a guess that it would be the same. by the way, down under here in australia, we use the metric system so it's km/h, l/100km and i'm a gettin 17" wheels!!!!! heh, heh, heh. saturday, here we come!!!! __________________ 328i M-Sport, Estoril Blue, Carbon XP 35 Tint, front heated seats, black Dakota, Sports Suspension, Anthracite Headliner, HUD, Pro Nav, Sunroof, hk 600w, Bi-Xenon, 19" 403M wheels, Reversing Camera, DAB+, Xenon, BT Ext Connect, MST turbo intake pipe, MST Cold Air Intake, JB4 on Map 2 with Catless DP produces awesome performance in Sport.
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07-27-2005, 09:11 AM	#17
JVFan Lieutenant 36 Rep 515 Posts Drives: Very Well Join Date: Jun 2005 Location: Lloydminster, AB CANADA iTrader: (1)	Usually senseless add-ons are a domestic car thing....that fuel use needle has always made me wonder what the hell the point was...no one else, to my knowledge, needs to tell you that when you are accelerating you use more fuel than when you are decelerating....go figure.
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07-27-2005, 09:43 AM	#18
chrisbin Colonel 112 Rep 2,333 Posts Drives: 640i MSport Coupe Join Date: May 2005 Location: S.Wales, UK iTrader: (1)	Couldn't agree more......but they've been fitting them for ages now.....as have M-B....... __________________ Current: F13 640i MSport, e85 Z4 3.0i Previous - Alpina D3 BiTurbo E90 LCI Manual, 320d M Sport E92 Auto, 330i M Sport E92 courtesy of BMW UK....320i M Sport E92 Auto, 320d SE E90 Manual.
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