[swu]

I found that everytime when the engine rpm is around 800-1000, the energy control meter will be at the highest point. This happens on all situations including accelerating, breaking, and time when neither stepping on the gas nor break pedal.

For example, when you break from 3000rpm, the meter falls to 0, but when the engine reaches slightly below 1000rpm, the energy control meter moves from 0 to 20 (measured in L/100km) then quickly falls back down to 0. (Foot is on the break all the time, no gas applied)

Any idea why?

[txusa03]

i am no einstein, so this is just a guess. right before you take your foot off the gas pedal, you are using momentum (so no extra energy is exerted at this point). As you apply the break, it take energy to slow down the momentum of the car. not sure if that is true...do we have any physics major on the board...

[noflash]

Originally Posted by swu

I found that everytime when the engine rpm is around 800-1000, the energy control meter will be at the highest point. This happens on all situations including accelerating, breaking, and time when neither stepping on the gas nor break pedal.

For example, when you break from 3000rpm, the meter falls to 0, but when the engine reaches slightly below 1000rpm, the energy control meter moves from 0 to 20 (measured in L/100km) then quickly falls back down to 0. (Foot is on the break all the time, no gas applied)

Any idea why?

I noticed this THIS morning in stop and go traffic. I think it's a flaw, as my 328i never acted this way. At least I better not be getting 10mpg at idle and coasting!

[E90Fleet]

Engine uses more fuel at idle than when coasting

You would be surprized to learn howmuch fuel you waste a year waiting at traffic lights

[ward]

you can stop the meter from going to zero if you accelarate slower

but that wouldn't be much fun now would it

[fredtoo]

Originally Posted by E90Fleet

Engine uses more fuel at idle than when coasting

You would be surprized to learn howmuch fuel you waste a year waiting at traffic lights

I was thinking that this is the real reason for the start - stop button on our cars.

I was wondering how much input the "Greens" have on the domestic German market. Do you think they encourage stopping the motor while stuck in traffic?
My wife works for Swiss company (Germany = Switzerland ) and they have implemented a "No Idling" policy in the USA. I'm sure the same policy exists in Switzerland

[JamieA]

I was once told (by a European) that 30 seconds of idling is the break even point between leaving the car to idle and the petrol consumed re-starting the car from stop. I don't know where he got this info or if it was correct, but he practiced this religiously.

Because of the price of fuel, the Europeans seem to go to extrodinary lengths to conserve it.

[JamieA]

....anyway, blame the Honda S2000, I think that car was the first to re-introduce the concept to contemporary motoring. Does anyone know of a recent car earlier than that which featured the button?

[txusa03]

Originally Posted by noflash

I noticed this THIS morning in stop and go traffic. I think it's a flaw, as my 328i never acted this way. At least I better not be getting 10mpg at idle and coasting!

I disagreed with you on this, my 323 and my 325 was doing the same thing as the e90. maybe you got lucky and got a 328 that did not have that behavior.

[noflash]

Originally Posted by E90Fleet

Engine uses more fuel at idle than when coasting

You would be surprized to learn howmuch fuel you waste a year waiting at traffic lights

Um... when you are coasting your engine is idling. Unless you turn your car off.


Also, I think everyone here needs to reread the initial post.

This thread is about the fact that when you are coasting forward at 5mph or less with the engine revs at idle the mph meter shows the worst mph. As soon as you hit the brake and actually stop, it goes back to the best fuel economy -- although the rpm have not changed and the gas pedal has not been touched.

[E90Fleet]

Originally Posted by noflash

Um... when you are coasting your engine is idling. Unless you turn your car off.

Mixup in terminology here I think

I mean when in gear,moving and say reving 1000rpm

I think you meant what id call freewheeling ( moving with clutch pushed in )

[E90Fleet]

Originally Posted by noflash

Also, I think everyone here needs to reread the initial post.

This thread is about the fact that when you are coasting forward at 5mph or less with the engine revs at idle the mph meter shows the worst mph. As soon as you hit the brake and actually stop, it goes back to the best fuel economy -- although the rpm have not changed and the gas pedal has not been touched.

Actually he says the car shows its using "0 litres per 100km", then goes to "20 litres per 100km" then drops back to "0 litres per 100km"

So from using no fuel, to using quite a bit to using no fuel

[swu]

The meter moves up the max and down to 0 in about 4 seconds (like the system is testing the meter, the meter moves smoothly up to max and immediately moves smoothly back to 0). This does not happen in idle, it happens slightly above idle but below 1000rpm.

[Broken1]

The reason the car does this is when you are idiling, the engine is consuming fuel.
For "stupid poeple reasons" BMW set the energy guage to return to 0 when the car comes to a complete stop, so that poeple don't complain that their car is using petrol at a complete stop. When you are slowing down(near a complete stop), and you are no longer coasting...the engine starts requiring fuel to continue running, so the gauge goes up (ie worse fuel cons.) - when you get to your complete stop, the gauge returns to zero, like it's be programmed to do.

Easy huh?

[JamieA]

Originally Posted by Broken1

The reason the car does this is when you are idiling, the engine is consuming fuel.
For "stupid poeple reasons" BMW set the energy guage to return to 0 when the car comes to a complete stop, so that poeple don't complain that their car is using petrol at a complete stop. When you are slowing down(near a complete stop), and you are no longer coasting...the engine starts requiring fuel to continue running, so the gauge goes up (ie worse fuel cons.) - when you get to your complete stop, the gauge returns to zero, like it's be programmed to do.

Easy huh?

Groan - that makes me hate this gauge even more now that I know it is dumbed down

[E90Fleet]

Originally Posted by Broken1

The reason the car does this is when you are idiling, the engine is consuming fuel.
For "stupid poeple reasons" BMW set the energy guage to return to 0 when the car comes to a complete stop, so that poeple don't complain that their car is using petrol at a complete stop. When you are slowing down(near a complete stop), and you are no longer coasting...the engine starts requiring fuel to continue running, so the gauge goes up (ie worse fuel cons.) - when you get to your complete stop, the gauge returns to zero, like it's be programmed to do.

Easy huh?

Think about it, when you are standing still the guage should read in infinity, because you are no moving ( so you would use infinity litres to reach 100Km )

I think the guage "switches off" when you are moving to slow/standing still, thus showing 0

[Broken1]

Originally Posted by E90Fleet

Think about it, when you are standing still the guage should read in infinity, because you are no moving ( so you would use infinity litres to reach 100Km )

I think the guage "switches off" when you are moving to slow/standing still, thus showing 0

I concur Dr.

That would make sense...
I noticed on the E34 535i I was driving before my E90, that when you came to a complete stop, the gauge would go upto 30l/100km's then past it, under the dash - so you couldn't see the needle anymore.
You would only see it again when you started cruising and the cons dropped...

[billgti]

Originally Posted by E90Fleet

Think about it, when you are standing still the guage should read in infinity, because you are no moving ( so you would use infinity litres to reach 100Km )

I think the guage "switches off" when you are moving to slow/standing still, thus showing 0

in US spec cars, our gauges do the same thing (i.e. when fully stopped, gauge goes to max efficiency/mileage) but since we measure in mpg, the calculation works out to be 0 mpg, not infinity like in l/km.

[scottz5]

Originally Posted by JamieA

I was once told (by a European) that 30 seconds of idling is the break even point between leaving the car to idle and the petrol consumed re-starting the car from stop. I don't know where he got this info or if it was correct, but he practiced this religiously.

Because of the price of fuel, the Europeans seem to go to extrodinary lengths to conserve it.

I dont think this is true once a gas engine is warm. Look at all the gas/elec cars work. They all shut off when they come to a stop.

Today I filled up and drove like a old man and had an avg. of 25mpg local back roads at 55-60mph in 6th gear. Some stop and go but i was watching the gauge close.

[noflash]

Originally Posted by E90Fleet

Mixup in terminology here I think

I mean when in gear,moving and say reving 1000rpm

I think you meant what id call freewheeling ( moving with clutch pushed in )

Agreed.

Still, MY question is why would the gauge show the worst gas mileage (for instance that you would get at WOT) when the rpms are at the lowest running speed and the gas pedal is not being applied?

Hiccup in logic at best.

[billgti]

Originally Posted by noflash

Agreed.

Still, MY question is why would the gauge show the worst gas mileage (for instance that you would get at WOT) when the rpms are at the lowest running speed and the gas pedal is not being applied?

Hiccup in logic at best.

maybe because without applying any gas and rolling along at idle is the equivalent of 12mpg. even tho u r not applying any throttle, the engine is using gas.

[txusa03]

I still don't think it is a hicup or flaw because it has alway been like that with e46 323 and 325. Just because I don't understand the logic behind it, does not always mean flaw. We really need to talk to a BMW engineer to understand this. True, there are flaws even in beamer, but not this energy meter, cannot be a flaw for all these year. just my opinion.