Just wondering if someone could explain how the fuel display fluctuates so much.
Yesterday it said 43 miles remaining, today after driving on the motorway for a little while it has gone up to 62 miles remaining, without adding fuel ?
I can see that the gauge is dropping as the fuel is used but why such a fluctuation in miles remaining ?
It uses the last few miles you have been driving to calculate how far you can go if you continue the same way.
So coming from urban area out on the highway, your consumption goes down, and after a while it will start adjusting and increasing the distance left until empty.
And vice versa.
Is that the explanation you were looking for?
Thanks for that.
Mine fluctuates quite a bit.
They do, because consumption fluctuates quite a bit.
I donāt think you car is unique in that aspect. 
Yes, it fluctuates according consumption of last 10 km for me. Sometimes travelled 50 km and remaining distance is higher as was on start.
Also average consumption on day counter vary. I found that relevant is after engine shutdown. If you check it during travelling and then compare after stop the difference is quite significant.
So actually means nothing! All these fancy features, but the Rivoli doesnāt include a windscreen washer reservoir level warning!
Itās very useful if you understand how it works.
It would be extremely difficult to use (i.e. useless) if the number was static.
It canāt be exact because conditions are changing. Anyway, agree with the windscreen fluid level indicator, thatās sucks. It is a shame for DS.
I guess Iām fortunate that - so far at any rate! - this is my only real gripe about my DS4 (okay, actually my second real gripe as neither the āMyDSā app or the āScan MyDSā app work!), the range estimate in the digital display really is all over the place and, accordingly, is all but a meaningless metric to me (as is the average speed metric!).
Currently I have an estimated range of 285 miles in the tank but I can all but guarantee that by the time I drive the 1/2 mile or so out of my small cul-de-sac and onto the main road it will have dropped by a minimum of 10-12 miles. It will then continue to drop in an entirely disproportionate way to the length of journey undertaken, sometimes dropping off the edge of a cliff and on other occasions reducing only marginally over 10/20/30 mile runs. Aaaarrrggh!!!
This is indeed explained by what DsJay has posted but it nonetheless makes the range meaningless to the majority of drivers 
Iām not convinced the average mpg is all that accurate either (mine is 44mpg) but surely using this figure and the volume of remaining fuel in the tank (ie 5 gallons left meaning 220miles of range) would give a far more accurate, consistent and meaningful range estimate as opposed to using the last few miles of driving (which will often vary hugely as has been spoken about) to extrapolate from as that change from mile to mile is at the root of wildly fluctuating range figures?
Just an update to underline this (if anyone is even remotely interested!!) - Iāve just dropped my dog off at the groomers, a round trip of just under 9 miles on roads with no traffic congestion and speed limits mostly at 30mph but approx 3 miles of the journey at 60mph, and my estimated fuel range has dropped by 50 miles. When I make the round trip again to pick the dog up Iāve no idea how much the range will drop by.
This evening Iām picking my wife and a friend up from the Theatre, a round trip of approx 45 miles, and Iāve no idea whether the current range on the digital display (105 miles) will get me to the groomers and back and then to the Theatre and back. Iām probably exaggerating here to make the point as I can see Iāve a third of a tank remaining and, if my average consumption is correct (no guarantee admittedly!), then I do have sufficient petrol. However, I shouldnāt have to do this mental arithmetic to see how far I can travel with the remaining fuel as this is how the trip computer should calculate the approximate range (I know it can never be exact due to varying driving factors) and not whatever messy way it currently is and which renders the figure meaningless.
My guess is that it will drop with about as much as the distance you will be driving.
The TC (Trip Computer) should in this case base its estimation on your last trip, which was the exact same trip, so now it should be fairly accurate (unless you make another trip in between with a different consumption level).
Why it dropped 50 miles the first time, when you in fact only traveled 9 miles, must be due to a lower consumption the trip before that (in fact, the last few miles on the trip before that, not the whole trip).
Considering how much you struggle with these numbers, perhaps there is in fact a fault in your particular vehicle?
The change in mileage could be linked your present driving conditions. The car is constantly measuring available mileage on a trip; taking into account things like weather, hills, the amount of times you have to stop/start.
āNow, let me thinkā¦
If I drive 109 miles in my new DS at 33.33mph for 6 days over a bumpy field whilst carrying a cow in the passenger seat and an elf in the boot, my fuel consumption is less than if I drive 10 miles at 30 mph on a smooth road .
Why is this ???ā
āCome on Albert, think man, this is easy !ā
āThe answer is written behind me !!ā
āWhat confuses me is why you bought a DS in the first place.ā
I think I have found the algorithm that Stellantis (including DS) use, work for Petrol, Hybrid and EV vehicles.
Variables are:-
Quantuty of Fuel in tank = QF
Amount used in last 2 mile = D
Max speed in last 2 miles =S
So the formula is
((QFĆ·S) * D) /3.142 + Your Grannies age.
I think this would be infinitely more meaningful a formula than whatever it is that they actually do use 
It just may be that there is a fault, although given
thereās at least one or two others on this thread who might have similar frustrations Iām not entirely sure, I just think whatever formula the trip computer actually does use allows for way, way, way too erratic an estimation of range over any length of journey and must be including variables that should necessarily be evened out in the calculation - indeed, the calculation should simply be āfuel remaining in gallons x the mpg estimate the trip computer is displayingā (which is, Iād hope, averaged out over the many journeys previously undertaken and therefore evens out all the variables mentioned by others, variables which are adversely impacting any meaningful range figure in whatever calculation that is being used).
Apologies for ranting on!! 
In other words itās cr*p. 
āWe often laugh at what we donāt understand.ā
/Seth Milchick, Severance S02E04
Oh, I understand it, but whether the rate at which it fluctuates is useful or not is a personal choice.
