Mark P

In my 2002 S4 and 2008 A3, I believe it was (and was documented) such that the "miles to empty" really referred to the "miles to reserve capacity". That is, if my tank capacity was listed at 16.4 gallons, and I got to a gas station right when it changed to "0 miles remaining", filling up the tank would take around 14.5 gallons (leaving about 2 gallons still in the tank). The gas light would come on when there was 25-50 miles remaining (depending on car, driving mpg avg, etc).

It seems on my Q5, that when I hit "0 miles remaining", I have used the full capacity of the tank and I'm running on fumes. Reading the manual, it seems that the verbiage may indeed have been changed to reflect that (though it was always vague). It now says something to the effect of "when the gas light comes on, you're entering reserve", suggesting that when it reaches 0, it's indeed empty. The light still comes on with 25-50 miles remaining

Reinforcing this difference is I've tried to get to 0 miles and have so far filled up with most of my fill-ups at the full spec capacity. I noticed it the first time when I filled up with 18.85 gallons and thought I was going to have much more remaining. But since then also had:
19.84
19.60
20.02

Now I should also note that in my S4, I was able to fill another 1+ gallons into the tank/neck after the pump shut off the first time. I didn't routinely do this, but did know it was possible. I accidentally found out that this is not the case in the Q5 as I have already over spilled the tank. I wasn't trying to put a lot in, rather the pump shut off because I reached the $75.00 pre-authorized limit and so I restarted it and when I did, it hardly put any in (<0.5 gal) before spilling out. So maybe I still have more reserve past "0 miles" and I'm just being fooled because the tank is filling more by default.

Anyone have thoughts on this?

How far have you driven on "0 miles"?

Is this different with diesel?

I don't want to run my car empty to find out the limit, but would really like to know how much more is in there at 0 miles...

You can see some related data I captured years ago with my S4. Wow, that $1.69/gal 93oct was something, huh?
http://ctny.audiworld.com/mark/s4/ot...pty/empty.html

scrmorling

Sorry Mark, can't help. You imply it in your comments but, FWIW, I try not to run the tank to empty. It might not be an issue with today's fuel technologies and it might not be an issue with a new car but I have always been concerned about picking up the crud from the bottom of the tank if I ran it essentially to empty. Steve

idale

I prefer the $0.99/gal 93 I was getting in late 2001 for my Passat!

My 2002 Passat worked the same (gee, wonder why?), and I liked knowing that there were still a couple gallons left, both for in case I got to E and to avoid running too low and burning out the pump and stuff.

The one consolation for me is that with the TDI hopefully I'll get enough mileage from a tank that I can fill up early without feeling like I'm filling up "all the time". But my typical range will remain to be seen once it comes in (the boat unloaded today so hopefully mine was on it and I'll be getting it in the next week to week and a half). We should really fill up more frequently anyway, we're just all lazy about it.

NABS4

When the range remaining shows "0" on my car, there's about 7-8L remaining in the tank (roughly 2 gal).

Mark P

Ha, yes, I'm well aware of the costs of fuel "back then" - here's my running graph for the past decade+

Mark P

Thanks. How do you know? You drove some distance further after empty, or what?

I've looked around elsewhere and think I'm starting to believe this more (ie, they didn't make any change to the trip computer per se, but rather the tank is underrated for capacity)

Mark P

Agreed, particularly with diesel as I believe the engine/parts relies on the lubricity of the fuel. I believe there are systems to shut down the car upon fuel getting that low, but I don't feel like trying those out . I'm also not sure how an automatic deals with running out of fuel. As someone who has almost only owned stick shifts, it scares me to think of an automatic abruptly stopping, but I guess that's not realistic, safety-wise. In a stick, throwing in the clutch is just a natural motion to continue rolling to a stop. I don't recall if I ever ran out of gas in my S4, but I certainly ran it really low when headed to the drag strip to replace the 93oct with 104

MP4.2+6.0

what I think Audi says. I have always taken 0 miles on the display to mean it's done and virtually out of gas. And, its very accurate by most car standards. It isn't remotely like either my Chrysler or Toyota minivans of yore where they could go 30 miles + beyond the supposed zero miles--and I tested it many a time, and knew from the fills at the station there were miles to spare. Even ran 30 miles past empty pulling a trailer in the Toyota once--on a grade in the boonies--that was admittedly a nail biter.

With Audi's its pretty simple--run it to zero miles and then pull in to a station and fill it. Obviously better if you are in town with lots of stations. On both my 2000 A6 that holds approx 21.1 gallons (80L) and my D3 A8 that holds 23.7 gallons (90L), when I run it to zero miles, I can pump in within a couple tenths of a gallon of the capacity sometimes; normally it is within its last gallon by then across many tank fill ups when watching it. Sounds pretty similar to what you are experiencing at the pump on the Q5 so far too.

Another real world example, that taught me never to go below zero on an Audi. Coming home on a Peninsula freeway I looked down and forgetfully noticed it said 5 miles to empty, then zero on my then couple year old 2000 A6 4.2. But I had 10 miles to go and there are no roadside gas stations on that freeway (280). Well, within 5 miles of it saying zero, I rounded a long sweeper and it caughed and that was it. First and only time I used AAA gas service. Years later on the same stretch I saw the same readings on my A8 W12. Lesson learned: I took the 3 mile detour and got to the other town's station immediately, and pretty much pumped within a couple of tenths of 23.7 gallons to confirm once again to obey the display. A few times I have pumped past 24 gallons with it (and past 21 on the A6), but suspect the gas station vapor system was sucking off my metered and paid for fuel--CA station vapor systems are much more stringent than most states.

First time I had a miles to empty display on an Audi was my 1985 5000. You could actually calibrate it if needed, but likewise it was essentially empty when it hit zero.

Thus 0 =0 on my Audis, and with stereotype Germanic precision they are nothing like the laughably inaccurate ones I have had in other makes, also including their laughably optimistic fuel economy feel good displays that were 15% high/inaccurate too.

On a side but overlapping note mentioned some months ago in other threads my several posters, I have also found the gauge is somewhat non-linear on my Q5 Hybrid. It stays near full a long time before dropping. It feels like at a supposed half tank though it is now probably at less than half, or in other words it then drops more quickly. Thus I suspect the gauge may read full even a few gallons short of true full. Meanwhile, early on with a tank I feel from the readouts, the fuel gauge and the trip meter I will get lots of miles out of it, but by the lower half of the tank reality sets in.

NABS4

Because at 0, I pumped ~67L of gas, and according to Audi the tank capacity is 74L.

josedebardi

At 0 (and at one point 7 miles beyond 0) the most I have squeezed in is 73l. So not much to spare...