tallers

I was on my way home and forgot I needed gas while on the PA Turnpike. I was 15 miles until the next exit, my gas tank needle was riding "E" and the computer said I had 20 miles to go before empty. I was sweating my drive hoping to make the next exit, and if lucky, a nearby gas station. When I got to the exit my car said I had 5 miles until my gas tank was empty, needle still riding "E".

Luckily a gas station was close by so I filled my tank. I was able to add 13.954 gallons. When I got home I checked my manual which states I have a 16.9 gallon tank which includes a 2.1 gallon reserve.

So, assuming I had nearly 3 gallons until empty, why does the computer state "5 miles until empty"? Do you think it doesn't take into account the reserve? Has anyone driven where the computer said "0 miles until empty" or even "-miles until empty"? If so, when does it truly hit bottom?

I usually don't let it get this low but I also like to know exactly where I stand regarding the amount of gas left in the tank.

JohnBoyToo

Now you know where you stand on your car
and it was guessing how far you could go based on combined stop and go/city/highway mpg, if you were on the hwy then your mpg is actually a bit better...

or at least close to it, because the miles til empty is a guesstimate of how much you've used, how many miles,etc...

If the load changes, then the guesstimate is wrong...
if the a/c is on or not, if the hills and or traffic is worse, if your gas gauge is off by 10%, if you've changed tire diameters and the calculation is off

There are SO many bad things that come from running it down to where it picks up the sediment, etc... just don't !

NWS4Guy

It also tries to guess how far based on how you have driven the last time since you got in the car (both in terms of the type traffic you have been in and how aggressive you have been) suddenly driving on the freeway after being on side streets and then staying out of the pedal aggressively, will take a while to register on the distance to empty I have noticed.

Stereodude

Well, would you rather have a car that tells you that you have 10 miles until empty and then dies because it's out of fuel or one that tells you you've got 0 miles until empty and lets you drive another 20 miles?

In general any car maker is going to have the distance to empty calculation be conservative so that they don't have customers running out of gas.

gk1

Personally I find the "miles to empty" indicator [if using 14.8 gallons as "empty"] to be quite accurate and it does not take into account the "reserve". You can go roughly 30 more miles after the miles to empty indicates 0 miles...but as others stated it is not a good idea. I like to believe it is the German way of avoiding people running out of gas. I can almost here the German engineers..."We will tell them they are empty but really there are 2 gallons left...."

redrocker55

The fuel also plays a roll to cool the fuel pump. So bathing it in 2 gallons of reserve gasoline helps add to longevity of the fuel pump.

atombomb33

From what I understand, the computer is calculating the "XX miles to empty" based on not including the 2.1 gallon reserve. That sounds about right in your scenario. That would leave a nice cushion "just in case" with that 2.1 gallons which can get you anywhere between 30-50 miles on average.

sakimano

doesn't it just average your usage data from the past 20 miles? I thought that's what Audi usually did.

UmIsThisThingOn

From the previous thread about this:

https://www.audiworld.com/forums/sho....php?t=2812506

I freaked out the first time this happened as I was no where near a gas station. When I filled up and saw that it took 15 gals, I was like WTF. Now I know I have roughly 20-30 miles till I'm on 'W' (for Walk).

IvanS4

The calculation for remaining miles intentionally does not take into account 'reserve' fuel capacity. Think about it - if it took into account the full volume of the tank, then there would be no reserve. It's designed to get an average driver to fill up their tank well before they'll have a problem.