Kilometres to empty tank - margin of safety

[JGEM]

The problem with 3 people using the one vehicle is that 2 of the 3 people assume that number 3 is doing the basic stuff like filling up the fuel tank!

And so it was today that after my wife and daughter had both used the car my daughter got home and said 'Dad, the km to empty on the speedo says 10km, you'd better get some diesel"

When I got into the XC60 it actually said "---km to empty tank". I'd never driven it this low before and as the BP garage I go to was about 6km away over a hilly route I worried a bit about whether I would make it.

Luckily all was well and I got there OK, but the tank took a record fill of 66.3 litres.

Given the tank has a nominal 70 litre capacity it implies to me that Volvo seem to have incorporated a margin of safety of approx 4 litres on the empty reading.

[IJMOK]

I’ve read somewhere that the “distance to empty” is based on your average consumption for the last 30 miles, it would also be very short sighted of Volvo not to give it some extra capacity for just these occasions, a bit like the “red zone” on the fuel gauge

I notice you’re driving a D5, these are very sensitive to low fuel, specifically the fuel filters clog causing all manner of fuel starvation issues.

Once took a D5 down to 1/8th (top of the red and aprox 100 miles on the guague) apparently I had an injector issue causing the car to cut out doing 120kph in the middle lane of a French motorway, with 4 kinds in the car. The immediate fix was more fuel to re pressurize the system to get us going again, but since then I never see much less than ¼ a tank

[NigelDay]

Originally Posted by JGEM

The problem with 3 people using the one vehicle is that 2 of the 3 people assume that number 3 is doing the basic stuff like filling up the fuel tank!

And so it was today that after my wife and daughter had both used the car my daughter got home and said 'Dad, the km to empty on the speedo says 10km, you'd better get some diesel"

When I got into the XC60 it actually said "---km to empty tank". I'd never driven it this low before and as the BP garage I go to was about 6km away over a hilly route I worried a bit about whether I would make it.

Luckily all was well and I got there OK, but the tank took a record fill of 66.3 litres.

Given the tank has a nominal 70 litre capacity it implies to me that Volvo seem to have incorporated a margin of safety of approx 4 litres on the empty reading.

A word of warning. A couple of years ago we were driving down the A1 and had a planned fuel stop at Shell Ferrybridge for my regular fill-up with V-Power. On arrival, the V50 display was showing 20 miles to empty. Unfortunately, they were out of stock, but I had a 5 litre can in the boot, so I emptied this, “confident” it would be sufficient to get me down to the next Shell station on the A614 at Ollerton. As we drove away from the station, I was a little surprised to observe the fuel gauge had not moved and the display was still showing 20 miles to empty. Then, it changed to –miles to empty. A few miles later, the inevitable happened. The display showed ‘Reduced Engine Performance’ and then the engine stopped. The RAC were called and the story recounted. The driver quickly explained that some cars do not “respond” to 5 litres addition once the tank is nearly empty. It needs 10 litres (which thankfully he had to sell me) for the gauge and pump to register. After 10 litres was added, all was well. Since then I have observed that 5 litres added to the tank when it just hits the 80 miles to empty is OK – the light goes out and the miles to empty rises to 150 or so. If I am planning to run much lower and be remote from a filling station, I keep a 10 litre can in the back ‘just in case’. I’m still puzzled at the design of a fuel tank which allows this strange effect, but I also noted in another post (RoyMacDonald in New D4 economy thread) a description of the fuel tank in an XC60 AWD (not like my V50, of course) perhaps straddling the transmission tunnel – ie, it is not a flat or single concave bottom. Perhaps there is a another explanation to do with pressurising the system, but whatever it is, don't rely on a 5 litre can for emergencies !

[Considered1]

Happened to me on a V60 test drive, stopped twice 15 miles from the dealers to add small amounts of fuel as computer wasnt recognising what was being added. Recovery guy added another gallon, took about 60 goes at starting the car. I Eventually took it back home (as it was late) and drove next day to the dealers without adding anymore fuel and there was still 150miles in the tank.

[craigv60]

The V60 also has a tank of 70 litre stated capacity, yet one time I ran my previous 2011 V60 D3 down to about 30 miles range remaining. I managed to squeeze in 71.5 litres ....

There's obviously an air gap to allow for fuel expansion in hot weather (not something we usually have a problem with in the UK ).

As others have said, generally it's better to fill up before you're running on the smell of an oily rag, but if your car didn't have any issues immediately before or after filling, it'll be fine.