Let us know how you get on.

First 20miles home were rather nervous as the range plummeted down to 30 miles. Then downhills and average speed cameras appeared, so it steadied and started to creep back up, until traffic jams saw it drop straight to --.

Made it home though, dropped off gear then trundled round to the garage and squeezed 72 litres in there.

Overall a bit too close for comfort, but interesting to know what the range really is at the low end.

I think I read somewhere that the last 30 miles are used to estimate fuel left. So as you would expect if you tread lightly as the range gets low the computer finds more range

Had a faulty fuel gauge on a 17tonne wagon once and ran out just short of a junction on the M32 in Bristol. I had some looks as I walked back up the hard shoulder with a 5l can of fuel. Turned out the regular driver knew about the gauge and I assume the boss wouldn't spend the money to fix it
Bit more involved to get going on the older non priming diesel systems. It was jack the cab up and get my emergency spanner out and crack of an injector pipe. There is then a starter button to press and once the fuel bleeds the engine starts and you tighten the joint. The fun bit is you are sitting on top of a 7 litre six pot diesel while all this happens. Not for the fait hearted

Many would say to get the fitter out, but when you are on 'job and finish' you want to get home

Volvo issued the advisory recently about not letting the fuel level fall below 3 bars. A diesel pumps more fuel to the engine than it uses and spills the spare back to the tank. This has an added advantage in the winter that it warms the fuel left in the tank and in olden days reduced waxing issues. The volvo tank has a spill compartment and that then overflows back into the main tank from where the engine supply is drawn. There is some coding issue in the ECU that in certain conditions there is not enough fuel between those divisions to keep the engine supplied

All these new assistances are nice to have but things are so complex now it's a bit of a trade off

That's rather bizarre. Is this the 'issue' which has been the subject of the recall for the D5 to update the software ? If so, I assume (for some reason) it does not affect the D4. The problem with this advice is that it goes against the 'advice' given by the display which asks if you want the system to search for the nearest filling station when you reach ONE bar.
Is there a link to this advice or was published in a TJ ?

The return feed into the spill compartment certainly explains my earlier problem with my V50 when 5 litres was insufficient to 'refresh' a near-empty tank.

I got an official letter advising not to let my vehicle fuel level go below the three bars. I will dig the letter out to get the date it was sent. I think it was only Penta engined cars, so D4/D5. As far as I remember the VEA is exempt, but then it is infested with Turtles, so doesn't need more challenges

My Defender just spills and feeds from a flat tank, but then it is basic engineering. I assume the XC60 has a tank that spans across the prop shaft, which would explain the two regions in the tank

No. That was for the software not displaying the correct information from the fuel sensor according to the info my dealer has from Volvo. The temp fix before the new software update was not to go to 1 bar on the display.

Coming home from holiday we travelled 610 miles on the fill up of diesel I bought in Inverness and I had enough left for another 80 miles when we arrived home so the range of a tankful is 690 miles depending on speed of course. When I got to Rye drove 12 miles and found the local garage was out of diesel so had to drive another 19 miles to the next one. Fill up took 68 litres. Not bad for the D5 auto fully loaded with stuff.

You were only pottering though. 641 miles to 68 litres at an average of ? MPH ?
c.42.8MPG

I remember taking my old S60 in to my indie in Nottingham with an average of 53.3MPG showing an average speed of 87MPH. When I got to the Dutch border that was reading 120MPH. I loved that EU III. My current EU V can't touch 50MPG driving like my granny.

Car companies will crack the latest legislation, the engineers will see light at the end of the tunnel and the EU (as is their wont) will buy some more tunnel.

Back to the original question, I usually find there is c. 1.5gallons or 6-7 litres in the tank when the light comes on. How far that will take you depends on how you've driven the last 30 or so miles.

Traffic was very heavy on the motorways and spent some time stationary. Journey time was 10:20 from Inverness to Rye. Approx. 62 mph.

If you 'spent some time stationary' and averaged 62MPH you must have been stretching 70MPH.
I've driven from Folkestone to Edinburgh overnight at a GPS 77MPH on the motorways (allowing for 50MPH roadwork sections) and only averaged 62MPH with no stops.

I ran mine down to 40kms to empty this morning. To the first click my S60 (approx 67litres tank) took 68,95litres plus the c.2,5 litres in there I reckon it will easily take 75litres to the brim. The slightly bigger XC60 fuel tank can probably nudge 80 litres.

My old S60 with 74 litres tank would hold about 82/3 litres. I often put 75 to 80 litres in it with it still showing 50 miles to empty (roughly 4,5 litres)