Question on this display to 45e owners...

aceman · 10-15-2020, 07:48 PM

How does BMW calculate range. The display by the fuel gauge states 291 miles of range to go. Roughly 5/8 of a tank or say 10 gallons.

I am fairly certain I am not averaging 29 mpg on the ICE.

Anyone have any ideas?

jad03060 · 10-15-2020, 08:02 PM

It's basing this on the history of how you've driven the vehicle recently, the current battery level, and what's in the tank. It's complicated, but yes, it's possible you might be seeing that. All bets are off if any of the conditions change.

Caramel · 10-16-2020, 01:55 AM

It also assumes the same electric / ICE mix that you have had for the last x kilometres. So that range indicator won't make any sense if you go on a longer trip (where you cannot constantly recharge the battery) after a lot of short trips (where you could always recharge the battery at the end of the day).

Sirksael · 10-16-2020, 02:52 AM

Indeed, the only place where you can see the Petrol only range, is on the BMW app. In my personal case, the range on the dashboard is pretty stable but that is only because i almost never use the ICE.

biterror · 10-16-2020, 03:08 AM

Quote:

Originally Posted by Caramel

It also assumes the same electric / ICE mix that you have had for the last x kilometres. So that range indicator won't make any sense if you go on a longer trip (where you cannot constantly recharge the battery) after a lot of short trips (where you could always recharge the battery at the end of the day).

This is very bad, IMHO. I need to know how far I can drive without stopping to refuel / recharge.

Caramel · 10-16-2020, 03:20 AM

Eventually you will work out a logic that each quarter of the tank will be good for x kilometres on the highway and then go by the fuel needle to estimate how far you can still go.

And while it is far from ideal, if you start your trip with a full tank of gas, then by the time that you have burned through half your tank, the system will have adapted to your driving style and show a good estimate on when you have to refuel again.

biterror · 10-16-2020, 04:21 AM

Quote:

Originally Posted by Caramel

Eventually you will work out a logic that each quarter of the tank will be good for x kilometres on the highway and then go by the fuel needle to estimate how far you can still go.

And while it is far from ideal, if you start your trip with a full tank of gas, then by the time that you have burned through half your tank, the system will have adapted to your driving style and show a good estimate on when you have to refuel again.

But if I first drive short trips for 2 months and recharge every night, then go on a long trip - doesn't the computer think "no worries, he will stop and recharge any moment now" and display an unrealistic range all the way?

I love the way my F11 (530d) works - it has a graphic range display with a marker that shows the destination and I can always see whether I need to refuel and how much range I'll have left at the destination. No surprises.

Caramel · 10-16-2020, 05:25 AM

The range forecast is based on your driving pattern over the last x km. Don't know what x is exactly, but let's assume that it would be 200.

As you embark on your trip, the car will think that you will stop and recharge often. Correspondingly, it will show an insane range. Yet as it learns that you never recharge during the first 200 km of your trip, it will understand more and more that it cannot rely on extra battery charges and gradually adjust the range down.

After 200 km (or more precisely: somewhere after 200 km and 200 km + electric range, say 250 km) it will show a realistic range forecast based on the assumption that you won't charge your vehicle for the remainder of the trip.

X5 45e · 10-16-2020, 06:11 AM

The economy on fuel only is around 10 l/100 km. So this is what you can expect when leaving with a full tank and not recharging during the trip. The tank is 69 l, 600-650 km should be no problem on fuel only depending of your driving style.

The range will decrease like Caramel says. The more you drive on a single trip the better the predicted range will come close to the real one.

And like mentioned the predicted range only is usable when driving longer trips. In other situations I just see if my tank is filled (usually is) and at the electric range.

It don't think there would be an situation where the predicted range is 800 km with only a quarter the fuel tank left. And if that situation should occur on departure on a longer trip it would make sense to fill the tank before leaving.

biterror · 10-16-2020, 06:53 AM

Quote:

Originally Posted by X5 45e

It don't think there would be an situation where the predicted range is 800 km with only a quarter the fuel tank left. And if that situation should occur on departure on a longer trip it would make sense to fill the tank before leaving.

Well, I hope I can start testing soon. The longer trips I make are over 1000 km one way and gas stations can be over 100 km apart (and it has happened that a gas station has no fuel available).. :-)

Caramel · 10-16-2020, 07:28 AM

Wow! Good thing then that you can use the gas station's wall socket to recharge your car overnight in case you cannot source fuel from anywhere nearby

I bet very few people ever enjoyed that added benefit of a driving a PHEV

X5 45e · 10-16-2020, 08:09 AM

Quote:

Originally Posted by biterror

Quote:

Originally Posted by X5 45e

It don't think there would be an situation where the predicted range is 800 km with only a quarter the fuel tank left. And if that situation should occur on departure on a longer trip it would make sense to fill the tank before leaving.

Well, I hope I can start testing soon. The longer trips I make are over 1000 km one way and gas stations can be over 100 km apart (and it has happened that a gas station has no fuel available).. :-)

I would stop after 450 km. Worst case you wouldn't be able to refuel for 200 km isn't it?

biterror · 10-16-2020, 09:03 AM

Quote:

Originally Posted by X5 45e

I would stop after 450 km. Worst case you wouldn't be able to refuel for 200 km isn't it?

Yeah, I'll have to learn to refuel twice as often as before. I guess that's called Progress ;-)

LexxM3 · 10-16-2020, 09:33 AM

Quote:

Originally Posted by biterror

Quote:

Originally Posted by X5 45e

I would stop after 450 km. Worst case you wouldn't be able to refuel for 200 km isn't it?

Yeah, I'll have to learn to refuel twice as often as before. I guess that's called Progress ;-)

I guess you had a big fuel tank small engine diesel beforehand then (just looked it up, 530d could likely get 1300-1500km on a single tank on a highway, nice)? It's hard to imagine what you were expecting for this particular use case switching to a gasoline hybrid 2300kg SUV with a smaller tank than non-hybrid. In any case, cool thing about liquid fuel is you can bring more with you:
.

X5 45e · 10-16-2020, 11:25 AM

Quote:

Originally Posted by LexxM3

Quote:

Originally Posted by biterror

Quote:

Originally Posted by X5 45e

I would stop after 450 km. Worst case you wouldn't be able to refuel for 200 km isn't it?

Yeah, I'll have to learn to refuel twice as often as before. I guess that's called Progress ;-)

I guess you had a big fuel tank small engine diesel beforehand then (just looked it up, 530d could likely get 1300-1500km on a single tank on a highway, nice)? It's hard to imagine what you were expecting for this particular use case switching to a gasoline hybrid 2300kg SUV with a smaller tank than non-hybrid. In any case, cool thing about liquid fuel is you can bring more with you:
.

I had a 530d in Europe that is not really a small engine, great power and torque. A small engine would be the 518d.

X5 45e · 10-16-2020, 11:26 AM

Quote:

Originally Posted by biterror

Quote:

Originally Posted by X5 45e

I would stop after 450 km. Worst case you wouldn't be able to refuel for 200 km isn't it?

Yeah, I'll have to learn to refuel twice as often as before. I guess that's called Progress ;-)

O well a stop every 4 hours and a breath of fresh air isn't so bad. But I get the point.

aceman · 10-16-2020, 08:07 PM

Lots of posts...but I think I have the answer for BMW to fix this.

Hey BMW, can the range be: Gallons of gas left x avg mpg + electric range left?

Thanks BMW. Why they make something that should be so damn simple to be complex/not accurate is beyond me...

Aceman

jad03060 · 10-16-2020, 08:17 PM

Many of today's vehicles calculate a range to empty. My last BMW did, and the two I have now do as well. On my GT, after a long trip, it might say over 500-miles to empty after a fill-up. BUt, then use it for stop and go around the city, and after a fairly short time, that might drop to 300-miles, a 40% drop in maybe 20-miles of driving. This isn't unique to BMW. The computer is programmed to produce a moving average of what's available for fuel, in this case either electricity or petrol, and makes a projection that if you continue in the exact same manner, how far you can go to IF you continue as you have been.

I don't know if the X5 works this way (haven't driven it much yet), but on the i3, if you put a destination to the nav system, the estimate on range becomes more accurate since the computer then knows the speed limits and terrain along your intended path. Otherwise, it has no idea how you're going to drive, or where you will be driving, so guesses that you'll continue as you had been.

The computer and car is not omniscient...it can only make guesses on the best available information and the skill of the programmers.

LexxM3 · 10-16-2020, 08:30 PM

Quote:

Originally Posted by aceman

Lots of posts...but I think I have the answer for BMW to fix this.

Hey BMW, can the range be: Gallons of gas left x avg mpg + electric range left?

Thanks BMW. Why they make something that should be so damn simple to be complex/not accurate is beyond me...

Aceman

Let's test how simple it is: please unambiguously define a single "ave mpg" value for all situations.

aceman · 10-16-2020, 09:05 PM

I would say use the avg from the last 250 miles driven - that should be a good indicator of driving habit. In my case - there is NO WAY if I drive the 11 miles of electric range, that I have 280 miles of range on the ICE w/ appx 10 gallons of fuel. The number is no where near accurate unless the fuel gauge is off/malfunctioning.

jad03060 · 10-16-2020, 09:17 PM

Except in very unusual circumstances, say a long-distance ride, most people's driving varies. On the i3, the average is based on the last 18-miles or so of driving unless you put in a destination, where then, it assumes you'll drive the speed limits and it knows the terrain...then, it can give a more exact estimate.

250-miles is certainly possible to estimate, but if most of that was stop and go in the city, then you wanted to drive on vacation 1000-miles, the results would be way off while now driving on a limited access highway without needing to stop or accelerate and slow down frequently. And conversely, you just get back from a holiday after driving home 250-miles on the motorway, and now are going back to your slow speed slog in stop and go traffic to go to work and run errands, how long do you want it to still be showing your mileage from the highway trip home? My guess is that the X5 uses about the same moving average window.

A moving average over a shorter period of time seems much more reasonable to me. After 20-30 miles once you start your trip, you'll have a much better idea of how far you can go before you need to stop and fill up.

biterror · 10-17-2020, 06:40 AM

I think my biggest problem with (how I believe) the estimated range calculation works is that it expects you to recharge one or more times to actually achieve the displayed range. (Ie. keep driving the same you have done in the past.) If it really works this way, it's about as useful as displaying "infinite" as the range and expecting you to refuel when needed.

The display should show how far you can drive _without_ refueling/recharging. That's how it has worked on all my cars before.

I understand that the fuel and electricity consumption varies, and it has to be taken into account - but this is a completely different thing.

10-15-2020, 07:48 PM	#1
aceman Second Lieutenant 110 Rep 209 Posts Drives: 2012 BMW 550ix, 2008 Corvette Join Date: Aug 2010 Location: NJ iTrader: (0)	Question on this display to 45e owners... How does BMW calculate range. The display by the fuel gauge states 291 miles of range to go. Roughly 5/8 of a tank or say 10 gallons. I am fairly certain I am not averaging 29 mpg on the ICE. Anyone have any ideas? Attached Images
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10-15-2020, 08:02 PM	#2
jad03060 Major General 3161 Rep 6,800 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	It's basing this on the history of how you've driven the vehicle recently, the current battery level, and what's in the tank. It's complicated, but yes, it's possible you might be seeing that. All bets are off if any of the conditions change.
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10-16-2020, 01:55 AM	#3
Caramel Second Lieutenant 129 Rep 243 Posts Drives: blue car, grey car, white bike Join Date: May 2020 Location: brussels iTrader: (0)	It also assumes the same electric / ICE mix that you have had for the last x kilometres. So that range indicator won't make any sense if you go on a longer trip (where you cannot constantly recharge the battery) after a lot of short trips (where you could always recharge the battery at the end of the day).
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10-16-2020, 02:52 AM	#4
Sirksael Private First Class 103 Rep 159 Posts Drives: X5 45e Join Date: Mar 2015 Location: Belgium iTrader: (0)	Indeed, the only place where you can see the Petrol only range, is on the BMW app. In my personal case, the range on the dashboard is pretty stable but that is only because i almost never use the ICE.
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10-16-2020, 03:20 AM	#6
Caramel Second Lieutenant 129 Rep 243 Posts Drives: blue car, grey car, white bike Join Date: May 2020 Location: brussels iTrader: (0)	Eventually you will work out a logic that each quarter of the tank will be good for x kilometres on the highway and then go by the fuel needle to estimate how far you can still go. And while it is far from ideal, if you start your trip with a full tank of gas, then by the time that you have burned through half your tank, the system will have adapted to your driving style and show a good estimate on when you have to refuel again.
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10-16-2020, 05:25 AM	#8
Caramel Second Lieutenant 129 Rep 243 Posts Drives: blue car, grey car, white bike Join Date: May 2020 Location: brussels iTrader: (0)	The range forecast is based on your driving pattern over the last x km. Don't know what x is exactly, but let's assume that it would be 200. As you embark on your trip, the car will think that you will stop and recharge often. Correspondingly, it will show an insane range. Yet as it learns that you never recharge during the first 200 km of your trip, it will understand more and more that it cannot rely on extra battery charges and gradually adjust the range down. After 200 km (or more precisely: somewhere after 200 km and 200 km + electric range, say 250 km) it will show a realistic range forecast based on the assumption that you won't charge your vehicle for the remainder of the trip.
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10-16-2020, 06:11 AM	#9
X5 45e Colonel 1091 Rep 2,420 Posts Drives: BMW X5 45e Join Date: Dec 2019 Location: Belgium iTrader: (0)	The economy on fuel only is around 10 l/100 km. So this is what you can expect when leaving with a full tank and not recharging during the trip. The tank is 69 l, 600-650 km should be no problem on fuel only depending of your driving style. The range will decrease like Caramel says. The more you drive on a single trip the better the predicted range will come close to the real one. And like mentioned the predicted range only is usable when driving longer trips. In other situations I just see if my tank is filled (usually is) and at the electric range. It don't think there would be an situation where the predicted range is 800 km with only a quarter the fuel tank left. And if that situation should occur on departure on a longer trip it would make sense to fill the tank before leaving.
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10-16-2020, 07:28 AM	#11
Caramel Second Lieutenant 129 Rep 243 Posts Drives: blue car, grey car, white bike Join Date: May 2020 Location: brussels iTrader: (0)	Wow! Good thing then that you can use the gas station's wall socket to recharge your car overnight in case you cannot source fuel from anywhere nearby I bet very few people ever enjoyed that added benefit of a driving a PHEV
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10-16-2020, 08:07 PM	#17
aceman Second Lieutenant 110 Rep 209 Posts Drives: 2012 BMW 550ix, 2008 Corvette Join Date: Aug 2010 Location: NJ iTrader: (0)	Lots of posts...but I think I have the answer for BMW to fix this. Hey BMW, can the range be: Gallons of gas left x avg mpg + electric range left? Thanks BMW. Why they make something that should be so damn simple to be complex/not accurate is beyond me... Aceman
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10-16-2020, 08:17 PM	#18
jad03060 Major General 3161 Rep 6,800 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	Many of today's vehicles calculate a range to empty. My last BMW did, and the two I have now do as well. On my GT, after a long trip, it might say over 500-miles to empty after a fill-up. BUt, then use it for stop and go around the city, and after a fairly short time, that might drop to 300-miles, a 40% drop in maybe 20-miles of driving. This isn't unique to BMW. The computer is programmed to produce a moving average of what's available for fuel, in this case either electricity or petrol, and makes a projection that if you continue in the exact same manner, how far you can go to IF you continue as you have been. I don't know if the X5 works this way (haven't driven it much yet), but on the i3, if you put a destination to the nav system, the estimate on range becomes more accurate since the computer then knows the speed limits and terrain along your intended path. Otherwise, it has no idea how you're going to drive, or where you will be driving, so guesses that you'll continue as you had been. The computer and car is not omniscient...it can only make guesses on the best available information and the skill of the programmers.
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10-16-2020, 09:05 PM	#20
aceman Second Lieutenant 110 Rep 209 Posts Drives: 2012 BMW 550ix, 2008 Corvette Join Date: Aug 2010 Location: NJ iTrader: (0)	I would say use the avg from the last 250 miles driven - that should be a good indicator of driving habit. In my case - there is NO WAY if I drive the 11 miles of electric range, that I have 280 miles of range on the ICE w/ appx 10 gallons of fuel. The number is no where near accurate unless the fuel gauge is off/malfunctioning.
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10-16-2020, 09:17 PM	#21
jad03060 Major General 3161 Rep 6,800 Posts Drives: X5 45e Join Date: Aug 2018 Location: NH iTrader: (0)	Except in very unusual circumstances, say a long-distance ride, most people's driving varies. On the i3, the average is based on the last 18-miles or so of driving unless you put in a destination, where then, it assumes you'll drive the speed limits and it knows the terrain...then, it can give a more exact estimate. 250-miles is certainly possible to estimate, but if most of that was stop and go in the city, then you wanted to drive on vacation 1000-miles, the results would be way off while now driving on a limited access highway without needing to stop or accelerate and slow down frequently. And conversely, you just get back from a holiday after driving home 250-miles on the motorway, and now are going back to your slow speed slog in stop and go traffic to go to work and run errands, how long do you want it to still be showing your mileage from the highway trip home? My guess is that the X5 uses about the same moving average window. A moving average over a shorter period of time seems much more reasonable to me. After 20-30 miles once you start your trip, you'll have a much better idea of how far you can go before you need to stop and fill up.
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10-17-2020, 06:40 AM	#22
biterror Captain 514 Rep 803 Posts Drives: X5 45e 2021 Join Date: Aug 2020 Location: Random iTrader: (0)	I think my biggest problem with (how I believe) the estimated range calculation works is that it expects you to recharge one or more times to actually achieve the displayed range. (Ie. keep driving the same you have done in the past.) If it really works this way, it's about as useful as displaying "infinite" as the range and expecting you to refuel when needed. The display should show how far you can drive _without_ refueling/recharging. That's how it has worked on all my cars before. I understand that the fuel and electricity consumption varies, and it has to be taken into account - but this is a completely different thing.
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