D4 Distance to Empty Accuracy

[PJJ]

I have noticed that the D to E on my D4 (3.0 ltr)appears less accurate than my old D3. Most of my driving is out of the city & the D3 would go approx. 800klms before the fuel light would come on, giving me a range of about 900klms. With the D4 (only 3 tankfulls so far) the fuel light seems to be coming on about the 700klm mark. At that stage the D to E says I only have about 80klms left to go. So far the fuel economy of the D4 seems about the same as the D3. I am assuming the fuel tank capacity is the same for both, so is the descrepancy just a less accurate fuel guage in the D4?

Phil

[Drafrete]

That's a really good question PJJ. I had noticed the same myself. I now have just over 10k up on my D4 3.0 SDV6 and it looks like the range is about 100 KM less than my D3. I also notice that in the manual it states that the D4 will hold a minimum reserve in the tank and will shut down the engine before it actually starves of fuel. So I have put this down to the fact that the 5 or 6 litres or so that it is allowing for makes the difference.

[Stuart02]

Is the D to E consistent with how much is left based on how much you get in to the tank when filling?
There's quite a bit in a few threads about how the trip meter is optimistic about the average economy. I've actually found the opposite with respect to finding myself filling up before I need to based on the suggested D to E.
I also noticed once, after my better half got carried away driving in Sport mode for 400km around town, that the trip meter said her average fuel use was 19 l/100km... But I only got 60 litres into the car... ie 15 per 100, which I can believe.
In summary, I don't think the instant fuel consumption curve is normally distributed, and can be skewed either way depending on how you drive (evidenced by my wife and her lead foot!). So if that's how the car estimates the mean consumption, rather than just from total fuel by distance, it's very likely to be wrong, and so will the estimated distance to empty...
Discuss!

[rufusking]

I've been logging the D to E both before I refill and after along odometer / trip, Average Fuel Consumption Rate and the volume of fuel added (subtracting this from the stated capacity to give fuel left in the tank before refilling). My observations have been that the D to E is derived from some "Recent" average fuel consumption rather than the "Average" since the trip computer (A, B or Auto) was reset. I base this on what happens when I leave Melbourne with half a tank and hit the Princes Highway. The D to E substancially increases as I get a hundred plus K's at highway cruising. The reverse happens when I get back to Melbourne. The D to E might show 200km but after doing 30km in traffic the following day it's down to 100km. I think it's quite logical to use the "Recent" average consumption rate to give a more realistic D to E.
Now moving on to the litres/100km. I rearly get the displayed Average to correspond with the calculated. The calculated is always higher than the displayed. I have kept the "B" trip untouched since new so it gives me the long term Average and vary between "A" and "Auto" for driving use. I've found Auto easy to use and to add subsequent "Trips" easy. You have until the next switch off to add them.

[vnx205]

My observations have been that the D to E is derived from some "Recent" average fuel consumption rather than the "Average" since the trip computer (A, B or Auto) was reset.

Some vehicles certainly do that. I would have thought that they all did. It would definitely be much more useful if they work as you described.

[gghaggis]

IIRC, the handbook states that the low fuel light is triggered once there is a specific volume of fuel left in the tank (can't remember the figure - 8 ltrs?). This automatically sets the display to D to E mode, and I've always found a different figure being displayed, depending on how I've been driving the last 100km or so. So yes, I think it's based on some average metric.

On a side note, the Statesman I've had as a loan car for the last week displays a D to E figure that can vary between 380km and 540km within 20km or so!!

Cheers,

Gordon

[PJJ]

Thanks for all the replies, but where does that all leave us? On a good trip in the D3 (economical like), it wasn't uncommon for me to get in excess of 900klms before filling up. The manual states that the fuel tank capacity is 82ltrs, but I have put 92 in it a few times.( it was still running:))But the D4 seems to be a lot more conservative on the D to E readout & if the engine will shutdown before it runs out of fuel, does that mean I now have effectively less range than the D3? Seams crazy to me!

Phil

[PJJ]

Just thinking more about this -
What is the biggest fill that anyone has done in a D4? At this time I have only managed 74 ltrs With the fuel light on & D to E of 80klms.
Also, if the motor cuts out on low fuel, what is the procedure for a restart?
This is going to drive me Crazy:twisted:

Phil

[mike7]

Interesting read, I just returned from a trip up to the snow with a mate of mine in a D3 and me in my D4.

His L/100km figures were a couple of liters worse than mine the whole way on the computer but we both put it in exactly the same amount of fuel on return to home. we convoyed the whole way so exactly same distance etc. We both had 28L left in the tank and my D to E was 200km and his was 410km.

My L/100km figure was 8.5/100 according to the car but actual calculated by me was 11.5L/100km, way off.

[discotwinturbo]

Just thinking more about this -
What is the biggest fill that anyone has done in a D4? At this time I have only managed 74 ltrs With the fuel light on & D to E of 80klms.
Also, if the motor cuts out on low fuel, what is the procedure for a restart?
This is going to drive me Crazy:twisted:

Phil

The manual tells you how to restart it. Needs a minimum amount of fuel put in, then hold starter down for so many seconds, and a couple of other things. I will read up if it ever happens.

Biggest fill......179 litres ;-)

Brett....

[PJJ]

thanks Brett
Me thinks you may have a larger tank than standard;)-& yeah, I think I did read something about the restart procedure now I think about it:eek:

Phil

[mowog]

They certainly need a larger tank than the standard. Just watch your distance to empty plummet with a van attached!!

[Graeme]

What is the biggest fill that anyone has done in a D4? At this time I have only managed 74 ltrs With the fuel light on & D to E of 80klms.
That's about what my last fillup was after a day's drive of 675 kms and 70L to empty, with the fuel light coming on next morning after another 5 kms. My usage showed 10.2 but the CCF has been adjusted to get the usage closer to actual.

[PJJ]

Gday Graeme

Reading the manual again, it says the fuel light comes on "when the remaining fuel reaches a minimum of 12 liters giving an approximate range of 80 km." I suppose they are being conservative with that distance. (15ltrs/100) I reckon that a guesstimate figure of remaining fuel would be in the region of 20ltrs, not 12ltrs, assuming that the tank has the same fuel capacity as my old D3 - 92 ltrs.

Phil

[scarry]

I have noticed if the D to E ,says for eg.,300k's,but i have been doing a lot of city driving,if i go on a run,the D to E will change,and you will actually travel way further than the 300k's.

The vehicle seems to continually monitor the fuel usage & volume in the tank & change the D & E to suit.

I recently got 75l into mine with 20k's on the D to E readout,which is the most i have ever got into it.

I pity you guys who tow,as i don't,but still find the small tank a real PITA,particularly after having the D2 that i could get 90l into easily & used less fuel.

The other issue is the l/100k readout that is very inaccurate,but the stealers don't seem to be able to fix it.:mad:

[Dingmark Jim]

A slight bit off-topic, but I deliberately drove beyond the "remaining range 0" mark just to see how far it would go. Had a spare 20 litre jerry can of diesel onboard. I gave up (more like chickened out) when I'd done an additional 85 km after 0 remaining had been reached. I didn't notice any change in performance, and it certainly didn't cut out.

I personally wouldn't recommend people do this as a matter of course, as I'm told it uncovers the in-tank fuel pump, which can cause it to overhead. I just wanted to get some data.

Has anyone else run their tanks dry or well beyond the "remaining range 0" notice?

[gghaggis]

I ran my D3 until it stopped - indicated 55 km beyond "0 km range". Next roadhouse was 500m down the road!

Cheers,

Gordon

[Dingmark Jim]

Just for clarity, it was the 3.0 TDi D4 that ran at least 85 kms beyond the 0 kms point. My older petrol V8 D3 ran only 25 kms beyond the 0 kms remaining point before it suddenly died. There was no warning on the D3 - the engine just stopped.