Manual fuel consumption calculation

[Neverfuel]

I keep a running total of my MPG, for each fillup and monthly. I have never reset the manual MPG on the car, and it is proving to be extremely accurate - down to the nearest 0.1 mpg.

My question is - Does the system calculate the fuel consumption figure based on what is recorded by a sensor in the fuel tank, or is it a measurement of fuel passed through the engine?

 

[anko]

I have the same experience. Although my lifetime was reset twice in two years: half a year ago when I ran down my aux battery and yesterday when I pressed the wrong button

The car displays average as well as instant MPG. Calculating an instant MPG based on fuel level would result in a mess as fuel level is a value that jumps all over the place (with movements of the car) and is only valuable when averaged out over a somewhat longer timespan.

Also, I don't think the car knows the difference between full and really full and also not between empty and really empty.

For this I think it will be based on fuel flow not fuel level.

 

[jthspace]

I keep a running total of my MPG, for each fillup and monthly. I have never reset the manual MPG on the car, and it is proving to be extremely accurate - down to the nearest 0.1 mpg.?

Have you entered all of the info into Fuelly and see what it says? As you have such accurate info, it may be worth doing to see if there are any differences.

Jeff

 

[Neverfuel]

I keep a running total of my MPG, for each fillup and monthly. I have never reset the manual MPG on the car, and it is proving to be extremely accurate - down to the nearest 0.1 mpg.?

Have you entered all of the info into Fuelly and see what it says? As you have such accurate info, it may be worth doing to see if there are any differences.

Jeff

No I have a spreadsheet where I keep track of everything, including electricity use for charging, free fast charging etc. Maby uses something similar. I signed up to fuelly but decided I don't really like going online to enter my fuel use, plus I like to work out monthly mileage and MPGe.

 

[Neverfuel]

I have the same experience. Although my lifetime was reset twice in two years: half a year ago when I ran down my aux battery and yesterday when I pressed the wrong button

The car displays average as well as instant MPG. Calculating an instant MPG based on fuel level would result in a mess as fuel level is a value that jumps all over the place (with movements of the car) and is only valuable when averaged out over a somewhat longer timespan.

Also, I don't think the car knows the difference between full and really full and also not between empty and really empty.

For this I think it will be based on fuel flow not fuel level.

I think you are right - I watched the screen a couple of days ago on a long journey. The MPG figure increased slightly on manual while on EV but decreased gradually whilst on petrol series/parallel. I figure that if the manual figure is so accurate, that the automatic should be accurate too. If so, by using the %EV figure and the automatic MPG figure at the end of a trip, you should be able to work out the ACTUAL MPG of the engine without any grid charge in the battery.

 

[anko]

I have the same experience. Although my lifetime was reset twice in two years: half a year ago when I ran down my aux battery and yesterday when I pressed the wrong button

The car displays average as well as instant MPG. Calculating an instant MPG based on fuel level would result in a mess as fuel level is a value that jumps all over the place (with movements of the car) and is only valuable when averaged out over a somewhat longer timespan.

Also, I don't think the car knows the difference between full and really full and also not between empty and really empty.

For this I think it will be based on fuel flow not fuel level.

I think you are right - I watched the screen a couple of days ago on a long journey. The MPG figure increased slightly on manual while on EV but decreased gradually whilst on petrol series/parallel. I figure that if the manual figure is so accurate, that the automatic should be accurate too. If so, by using the %EV figure and the automatic MPG figure at the end of a trip, you should be able to work out the ACTUAL MPG of the engine without any grid charge in the battery.

Don't think that will work, as I believe the %EV also includes EV miles driven on non-grid charge. If you calculate MPG for the period the engine is running you will get the equivalent of 11 l/100 km or worse. Best would be to start a trip, drain your battery and reset the manual reading as soon as the engine fires up for the first time.