MPG read out on economy screen

[Carnut]

People claim to get specific MPG figures over 100 but how do you know? I drove from Poole to Sherborne today, got 16 mles on EV and MPG on 'Manual' was showing __,_ presumably because I was doing more than 99.9mpg.
When I reached Sherborne it had dropped to 80.0mpg because the I.C.E. had obviously been working.
So how do I know how many miles MORE than 99.9 I have achieved during the journey?
Since Misubishi show off, claiming up to 148mpg they should have a three figure read out.
I looked at the history graph but couldn't see what I was looking for. Being dim again???

 

[jdsx]

People claim to get specific MPG figures over 100 but how do you know? I drove from Poole to Sherborne today, got 16 mles on EV and MPG on 'Manual' was showing __,_ presumably because I was doing more than 99.9mpg.
When I reached Sherborne it had dropped to 80.0mpg because the I.C.E. had obviously been working.
So how do I know how many miles MORE than 99.9 I have achieved during the journey?
Since Misubishi show off, claiming up to 148mpg they should have a three figure read out.
I looked at the history graph but couldn't see what I was looking for. Being dim again???

I forget precisely how to do it, but if you swap to 'litres per km' or something (you may have to leave it on this for a while), when you change it back it will briefly display mpg over 100 :mrgreen: . I think this was sorted in the MY2016 update....
But I don't trust the MMCS in any case so I use 'fuelly'!

 

[Vince31]

Sorted on 2016 MY, mine shwed 999.9 MPG the other day after the ICE kicked in for a few seconds whilst I was still stationary before setting off.

 

[gwatpe]

The PHEV consumes 50ml of petrol the first time the ICE starts from cold. On a short trip, I see 0.1 to 0.2 L/100km if the ICE has started by mistake. The problem is amplified, the shorter the EV trip.

In the bigger picture, for a 50km EV round trip and the ICE has started, this costs me 50ml of petrol. If the drive had been hybrid, probably 5L/100km, so 2.5L of petrol. The 50ml amounts to about 4% for no benefit. There is some merit in finding some way to keep the ICE OFF if the drive can be EV only.

I find that the L/100km on the MMCS on older PHEV would always show a number if the ICE started or not. I did try the mpg, but seemed a backward step to try for bigger numbers for better economy.

 

[raymie]

I have not bothered to work out my MPG given that I have the heating blasting all the time at the moment and preheat the car but I charge up once per day (no charge point at work), drive 75 miles (not trying to be especially efficent fuel wise) and that is costing me 10l of petrol per day. So I guess I am getting nearer 35mpg, oh well.

 

[Pancake]

On the dashboard, there is the screen in the middle. It's possible to fiddle with it's setting by pressing the button you use to switch between the different screens (like leafs, S-awc, range, fuel consumption) for two seconds. That button it placed behind the steering wheel and barely visible.

I did not try it yet, but according to the manual it should also be possible to cancel the automatic "reset" of average fuel consumption. That's something i am going to try, because I'm more interested in average fuel consumption over a longer period.

 

[Neverfuel]

On the dashboard, there is the screen in the middle. It's possible to fiddle with it's setting by pressing the button you use to switch between the different screens (like leafs, S-awc, range, fuel consumption) for two seconds. That button it placed behind the steering wheel and barely visible.

I did not try it yet, but according to the manual it should also be possible to cancel the automatic "reset" of average fuel consumption. That's something i am going to try, because I'm more interested in average fuel consumption over a longer period.

If you change it to manual it should show you the fuel consumption since it was last reset. If you have never reset it, it will show fuel consumption since new.

 

[anko]

In the bigger picture, for a 50km EV round trip and the ICE has started, this costs me 50ml of petrol. If the drive had been hybrid, probably 5L/100km, so 2.5L of petrol. The 50ml amounts to about 4% for no benefit. There is some merit in finding some way to keep the ICE OFF if the drive can be EV only.

I agree, when it happens during a "beyond EV range" trip, it is all quite relative. But when circumstances are good, I can perform my daily commute of 2 x 40.5 km without burning any fuel. The 50 ml would then represent 100% of my total fuel consumption and an unneccessary cold start.

 

[jthspace]

On the dashboard, there is the screen in the middle. It's possible to fiddle with it's setting by pressing the button you use to switch between the different screens (like leafs, S-awc, range, fuel consumption) for two seconds. That button it placed behind the steering wheel and barely visible.

I did not try it yet, but according to the manual it should also be possible to cancel the automatic "reset" of average fuel consumption. That's something i am going to try, because I'm more interested in average fuel consumption over a longer period.

If you change it to manual it should show you the fuel consumption since it was last reset. If you have never reset it, it will show fuel consumption since new.

Top Tip - My display is now showing 61 mpg (4.6 L in 100km) since I have had the car (it had 300 miles on the clock when I got it, so do not know if the dealer had ever reset the display). Slightly different to the Fuelly figure, but . . . . . good enough for me.

*<|:-{)}

(tilt your head to the left to read the last line)

 

[Carnut]

I don't think I made myself clear.
When I was driving to Sherborne the EV expired and the i.c.e. started up but the manual (& auto) readings both showed _ _._ for about 10 miles and then started showing figures , ending up with 80.0mpg. (I had reset the system before I started so Manual & Auto readings both showed 80.00 at journey's end of 80.00mpg. When I start for home the auto will start off reading _ _._.
I wanted to find out what mpg I was doing with the ice running BEFORE it dropped to a readable figure. i:e: how much MORE that 99.9 did I achieve before the figures became visible.
I am quite aware that the figure shown on auto is only a one trip figure and it clears itself after 4 hours after the car is switched off.
Whereas the manual reading lasts for multiple trips showing an overall average until it is reset.
SO.... is there any way of finding out the BEST mpg I have ever achieved??

 

[anko]

I don't think I made myself clear.
When I was driving to Sherborne the EV expired and the i.c.e. started up but the manual (& auto) readings both showed _ _._ for about 10 miles and then started showing figures , ending up with 80.0mpg. (I had reset the system before I started so Manual & Auto readings both showed 80.00 at journey's end of 80.00mpg. When I start for home the auto will start off reading _ _._.
I wanted to find out what mpg I was doing with the ice running BEFORE it dropped to a readable figure. i:e: how much MORE that 99.9 did I achieve before the figures became visible.
I am quite aware that the figure shown on auto is only a one trip figure and it clears itself after 4 hours after the car is switched off.
Whereas the manual reading lasts for multiple trips showing an overall average until it is reset.
SO.... is there any way of finding out the BEST mpg I have ever achieved??

I believe you are chasing a number that does not exist. As soon as you have left your driveway, you have traveled a distance without burning fuel. This will resulting an infinitive (or is it infinite?) MPG. As long as the engine does not run, it will stay infinitive. When the engine starts running, it will gradually drop until it reaches the 80 MPG you ended up with. At that time every thinkable number between infinitive and 80 MPG has been valid at a some point during your trip. But it doesn't mean anything, other than you that have driven a while before the engine being start up.

 

[greendwarf]

I don't think I made myself clear.
When I was driving to Sherborne the EV expired and the i.c.e. started up but the manual (& auto) readings both showed _ _._ for about 10 miles and then started showing figures , ending up with 80.0mpg. (I had reset the system before I started so Manual & Auto readings both showed 80.00 at journey's end of 80.00mpg. When I start for home the auto will start off reading _ _._.
I wanted to find out what mpg I was doing with the ice running BEFORE it dropped to a readable figure. i:e: how much MORE that 99.9 did I achieve before the figures became visible.
I am quite aware that the figure shown on auto is only a one trip figure and it clears itself after 4 hours after the car is switched off.
Whereas the manual reading lasts for multiple trips showing an overall average until it is reset.
SO.... is there any way of finding out the BEST mpg I have ever achieved??

I believe you are chasing a number that does not exist. As soon as you have left your driveway, you have traveled a distance without burning fuel. This will resulting an infinitive (or is it infinite?) MPG. As long as the engine does not run, it will stay infinitive. When the engine starts running, it will gradually drop until it reaches the 80 MPG you ended up with. At that time every thinkable number between infinitive and 80 MPG has been valid at a some point during your trip. But it doesn't mean anything, other than you that have driven a while before the engine being start up.

This is not quite correct - once you burn any petrol there is a real number calculation based on mileage since last reset, which is unlikely to very large unless you have never used fuel and driven many miles in EV which is likely to be impossible due to the need to periodically refuel and dispose of it without using the ICE. However, you would need to be logging the mileage continuously and have the display in litres/km to see it and then convert back.

But what is the point? The only "real" mpg is for journeys completed without EV. Any other figure includes a proportion of EV miles which instantly skews the figure so as to be meaningless. :roll:

 

[maby]

I don't think I made myself clear.
When I was driving to Sherborne the EV expired and the i.c.e. started up but the manual (& auto) readings both showed _ _._ for about 10 miles and then started showing figures , ending up with 80.0mpg. (I had reset the system before I started so Manual & Auto readings both showed 80.00 at journey's end of 80.00mpg. When I start for home the auto will start off reading _ _._.
I wanted to find out what mpg I was doing with the ice running BEFORE it dropped to a readable figure. i:e: how much MORE that 99.9 did I achieve before the figures became visible.
I am quite aware that the figure shown on auto is only a one trip figure and it clears itself after 4 hours after the car is switched off.
Whereas the manual reading lasts for multiple trips showing an overall average until it is reset.
SO.... is there any way of finding out the BEST mpg I have ever achieved??

I believe you are chasing a number that does not exist. As soon as you have left your driveway, you have traveled a distance without burning fuel. This will resulting an infinitive (or is it infinite?) MPG. As long as the engine does not run, it will stay infinitive. When the engine starts running, it will gradually drop until it reaches the 80 MPG you ended up with. At that time every thinkable number between infinitive and 80 MPG has been valid at a some point during your trip. But it doesn't mean anything, other than you that have driven a while before the engine being start up.

This is not quite correct - once you burn any petrol there is a real number calculation based on mileage since last reset, which is unlikely to very large unless you have never used fuel and driven many miles in EV which is likely to be impossible due to the need to periodically refuel and dispose of it without using the ICE. However, you would need to be logging the mileage continuously and have the display in litres/km to see it and then convert back.

But what is the point? The only "real" mpg is for journeys completed without EV. Any other figure includes a proportion of EV miles which instantly skews the figure so as to be meaningless. :roll:

I don't think it is meaningless - fuel economy is an important consideration for most of us - either for environmental reasons or for cost savings. What we do need to do is to calculate a combined fuel economy figure that allows us to compare performance with other cars in some meaningful way. How you do that will depend on your particular priorities - financial or environmental - but either way, you can combine the cost per gallon with the cost per kWh or the CO2 emissions per km on petrol with the CO2 emissions per kWh of power generation to arrive at a combined figure.

 

[anko]

But it doesn't mean anything, other than you that have driven a while before the engine being start up.

But what is the point? The only "real" mpg is for journeys completed without EV. Any other figure includes a proportion of EV miles which instantly skews the figure so as to be meaningless. :roll:

If I was not correct, can you explain the difference between what I said and what you said?

You take off for a next trip, trip computer reset and all. As long as the engine has not fired up, you MPG will be infinitive, regardless of how few miles you have driven, as X miles / 0 galons = infinitive MPG, as soon as X is greater than 0. So, as soon as you leave the driveway with the engine off, this is the case. At some point, when you have burned the first drop of fuel (think 0.5 cc or something like that), the MPG number will be huge (think 22 miles divided by a 10,000th of a gallon = 220,000 MPG. But just before that, when you had only burned half a drop, it was even 440,000 MPG. And just before that, ....

At the end of the trip, when you have burned a reasonable amount of fuel, the MPG will have gone down from infinitive to a reasonable number. In the mean time both miles travelled and amount of fuel burned are continues functions of time (you don't jump from 5 to 10 miles in 0 time. Also you don't jump from 5 gallons burned to 5.5 gallons burned in 0 time). Consequently, an thinkable number between infinitive and the final number was valid at some point

 

[anko]

...
But what is the point? The only "real" mpg is for journeys completed without EV. Any other figure includes a proportion of EV miles which instantly skews the figure so as to be meaningless. :roll:

I don't think it is meaningless - fuel economy is an important consideration for most of us - either for environmental reasons or for cost savings. What we do need to do is to calculate a combined fuel economy figure that allows us to compare performance with other cars in some meaningful way. How you do that will depend on your particular priorities - financial or environmental - but either way, you can combine the cost per gallon with the cost per kWh or the CO2 emissions per km on petrol with the CO2 emissions per kWh of power generation to arrive at a combined figure.

I think you are missing the point. There are various MPG numbers that you can discuss, such as:
- MPG for the last trip (or any specific trip)
- lifetime MPG
- best MPG for your daily commute
- best MPG for any trip of exactly 100 miles
- and so on.

These are all valid and relevant values. And the do allow you to compare your car to a 'normal' car. But "Best MPG ever achieved", which Carnut is looking for, without specifying a trip profile is meaningless. Well, it will be infinitive, as soon as he has done a single EV only trip. And even if he hasn't done any EV only trips, than still any trip will have EV only sections and MPG over these particular sections wil again be infinitive. So the answer to Carnut's question would be infinitive and the answer would be rather meaningless. IMHO :mrgreen:

 

[Carnut]

Firstly

HAPPY CHRISTMAS TO EVERYONE.


Sorry if I have stirred up a hornets nest.
I am still trying to get round the complexities of hybrid driving.
Surely, with Mitsubishi claiming 'UP TO 148mpg', there is no way on earth a 2 litre petrol engine tugging a 2 ton lump will EVER get anywhere near that figure so they MUST be including OVERALL MPG using EV & i.c.e.
THAT is the figure I seek.
Enjoy your turkeys and have a fantastic day.

 

[jthspace]

Are you saying my PHEV is a Turkey?

:lol:

 

[anko]

To compare your personal achievements with the brochure overall MPG number you need to drive a total distance of 47.85 miles, starting with a fully charged battery, and see what you end up with.

This is because the brochure overall MPG number is simply derived from the brochure hybrid MPG figure (trip with empty battery) and assumes you can drive 32.31 miles before the battery is depleted (burning 0 fuel) and then drive 15.53 miles to get to the next charge point. So, the brochure overall MPG is the brochure hybrid MPG number * (15.53 + 32.31) / 15.53 or roughly the brochure hybride MPG * 3.

Sorry for the strange numbers, but in the Netherlands it would be 52 km (to flatten the battery) and the 25 km (to reach the next charge point). The 52 km depend on vehicle efficiency and battery size. The 25 km is a EU regulated constant. From this you can see that a bigger battery would result in a higher brochure overal MPG. As would a higher vehicle efficiency.

 

[greendwarf]

Thanks Anko for answering Carnut's underlying query - which is about comparing his usage against the claimed mpg. As you say, unless you repeat the EU test then the "best achieved" figure he was after is meaningless.

BTW I still think you are wrong about going through all possible numbers from infinity. The change from EV to ICE produces an instantaneous real number, which might be large, as I described, but nowhere near infinity. I'd say it is similar to the pressure change when a balloon bursts - adiabatic. :ugeek:

 

[anko]

BTW I still think you are wrong about going through all possible numbers from infinity. The change from EV to ICE produces an instantaneous real number, which might be large, as I described, but nowhere near infinity. I'd say it is similar to the pressure change when a balloon bursts - adiabatic. :ugeek:

Haha, bit off topic, but I like the discussion

The change from EV to ICE is not instantaneous, but it is a transition that takes time. 1/100th into that transition, you have burned 1/100th of the fuel associated with the transition and MPG will be 100 times as high as towards the end of the transition. And so on. But in the end, you are right. Because you cannot burn half a molecule and there a finite number of molecule in a gallon.