Adjusting Miles until Empty

Good afternoon forum,

I wanted to know if it was possible to adjust the miles to empty screen on my 2015 Audi A3 8V.

When I fill up my tank, it estimates my miles to empty way higher than actuality.

Adjusting fuel consumption adaptation doesn't seem to affect the miles to empty figure unless it takes X amount of miles or fill ups to re-calibrate.

Thank you in advance!

Best,
Brett

You're asking about This car?

How much does it mis-calculate it by? I don't have your car, but I do regularly drive another one with that feature and find the remaining tank range it calculates depends a lot on how the car has recently been driven.

Uwe said:

You're asking about This car?

How much does it mis-calculate it by? I don't have your car, but I do regularly drive another one with that feature and find the remaining tank range it calculates depends a lot on how the car has recently been driven.

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That's the car!

It's off by around 100 miles almost every time. When I top off the car, it says I have usually 340, 360 or 380 miles. When I fill up when there's about 25 miles left on the estimator, I have only driven about 240 to 260 miles.

The only time the miles to empty becomes accurate is when the tank is less than 1/4 full. It's way too optimistic after the initial fill.

Driving style doesn't change either between fills. I drive it aggressively and drive the same route 99% of the time for the past 52k miles.

How about your average MPG display? How does it correlate to actual miles driven for a tank full divided by the number of gallons you put in?

-Uwe-

Uwe said:

How about your average MPG display? How does it correlate to actual miles driven for a tank full divided by the number of gallons you put in?

-Uwe-

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The average mpg seems to be spot on, telling me that I'm averaging 19.2 mpg. It's just the estimated miles to empty doesn't reflect that. One hand isn't talking to the other.

IIRC the estimated miles to empty is based on consumption over approx the last 20 miles so it varies widely and, especially if you drive hard or in urban areas, is usually much worse than the longer term average meaning the miles left is usually ridiculously pessimistic as it approaches zero.

On my previous Audi RS4 (a 4.2L V8) the miles left after a fillup would usually INCREASE for the first 50-100 miles or so, then decrease to something meaningful until the range was around 100 miles or so and then fall rapidly again. Some RS4 owners reported regularly doing 50 miles (i.e. 2 gallons of fuel) while the miles to go showed zero...

The other factor would appear to be that it seems to assume the fuel tank is a regular cube and hence seems to linearly interpolate fuel level with quantity fuel remaining, which further worsens the accuracy of the miles remaining shown.

Like mention above , this is normal. My car does same thing , If my last trip was 44-45 Mpg , it will estimate 600 MTE.
If I had last trip 38-40 it will estimate 520-530 MTE. My avrage is almost always 40-42, but MTE is always different.

BTW I never go by that , I always look for gas gauge position .

Jetta said:

Like mention above , this is normal. My car does same thing , If my last trip was 44-45 Mpg , it will estimate 600 MTE.
If I had last trip 38-40 it will estimate 520-530 MTE. My avrage is almost always 40-42, but MTE is always different.

BTW I never go by that , I always look for gas gauge position .

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I also always look at the gas gauge position as well, I just thought maybe there was a way to make the miles to empty more accurate after a refill.

BMoneyBrett said:

I also always look at the gas gauge position as well, I just thought maybe there was a way to make the miles to empty more accurate after a refill.

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Almost certainly not, every car I've owned in the last 40+ years has had a non-linear fuel gauge, and every one that has had a miles to empty feature has been either optimistic or pessimistic at all times (never accurate) so IMHO the fuel gauge position and your knowledge of your car is the best miles to empty guide.

PetrolDave said:

Almost certainly not, every car I've owned in the last 40+ years has had a non-linear fuel gauge

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IMO, they've gotten somewhat better recently. A fuel level sensor just detects level, and can't account for the shape of the tank, but I think as instrument clusters have gotten more sophisticated, they've come to include a "map" (look-up table) that takes the shape of the tank into account.

PetrolDave said:

and every one that has had a miles to empty feature has been either optimistic or pessimistic at all times (never accurate) so IMHO the fuel gauge position and your knowledge of your car is the best miles to empty guide.

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Sure, sometimes optimistic, sometimes pessimistic is to be expected. I've taken off from home in our 2015 Touareg with it showing ~200 miles of range left, knowing it's 258 miles to my preferred fuel stop and gotten there with ~40 miles showing because the wife had been driving the vehicle around town for a week before we left. OTOH, if I'm in the midst of a highway trip, re-fuel it, and keep running on the highway for the whole new tank, it's usually pretty close to reality for the whole tank.

Hence I am a bit puzzled by the OP's statement that his estimate is 25-30% off when he refills his tank. I wouldn't expect that to be the case in a car as new has his. I wonder of the logic in his cluster after a refill is to start out using some arbitrarily programmed "expected" fuel consumption figure, which he never achieves due to his driving style?

-Uwe-

Uwe said:

IMO, they've gotten somewhat better recently. A fuel level sensor just detects level, and can't account for the shape of the tank, but I think as instrument clusters have gotten more sophisticated, they've come to include a "map" (look-up table) that takes the shape of the tank into account.

Click to expand...

Even my MQB platform Skoda Octavia has an almost predictable non-linearity that the gauge drops slower between full and 1/2 than it does between 1/2 and 1/4 - very similar to every previous car. So in my experience the non-linearity while it may have improved slightly is still pretty poor.

It wouldn't take much computer modelling of the fuel tank volume vs. level to almost eliminate this non-linearity, but customers don't complain about it enough so there's no incentive to spend the engineering time/effort to get it right

My volt has pretty accurate fuel and/or battery to zero remaining.

The screen even tells me exactly how many kw and/or gallons, and what range each were used since last full charge.

One thing I wish it did give is a better, direct indication of mile per kw.

But like most cars, once below a ~30 mile GAS range threshold, it just says LOW.

Anyway, what I have typically done on a new/unfamiliar car is fill up at gauged indicated halfway, and gauge empty. And also look up what the rated fuel capacity is.

In my younger days, before cars had fuel/trip calculators in them, I would run them completely out of gas (with a spare gas can handy, of course), just to find out how far below E I could go.

D-Dub said:

In my younger days, before cars had fuel/trip calculators in them, I would run them completely out of gas (with a spare gas can handy, of course), just to find out how far below E I could go.

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I've fastidiously avoided that on newer cars because I imagine that the high-pressure fuel pumps used on modern direct injected gasoline engines wouldn't appreciate being run dry at all.

-Uwe-

yeah I haven't run anything dry with fuel injection systems.

that said, I would *hope* that manufacturers account for that by shutting down the engine before the actual fuel line sucks air.

but I know what I get with a hope in one hand, and fart in the other.

Same problem here after I change injector's to get more quantity of fuel to run my TSI with E85.
I change "display value of consumption and operating range" to 115% that make's me only wrong by 5% compare to calculated Liter/100KM ( normale I have injector delivering 20% more)
But the MFD Kilometer remaining until empty is totally off it stays same as it was before changing the value to 115.
So I think those are not linked.

It's very annoying because when I come down to 60km remaining range every 5km driving I loose about 10 to 15km of range.

PS: before the injector swap the Consumption was spot on and the remaining range until empty was also quite accurate.