Prepare to be bored like youve never been bored before

The fuel light came on this morning on the way to work, which means ive got 7litres or 1.85gallons left in the tank.

Now the distance to work and back is a 40mile round trip roughly, mainly a-roads. Going on official fuel economy estimates, gives my remaining range as:-

Urban (40.9MPG) ~76miles

Extra Urban (64.2MPG) ~119miles

Combined (53.3MPG) ~99miles

So either way, even driving at the worst figures i should have no problem, possibly should get 2 days travel out of it. Theres still quite alot of scope though.

I bottled it and filled up after i got back home (40miles)

My question is what method would give the closest estimate for the number of miles left in the tank? (barring the above)

There are several on the vrs:

1. Analogue. Using the fuel needle. The dials small and hard to read, plus i dont know how accurate the reading is or how sensitive it is to incline or movement. So its a no go really

2. Digital. Using the multifunction display. This is really the heart of my problem, how trustworthy is the data? Its all linked as far as i know to the 'real time' mpg display, but that just seems to be a random number generator lol, a flick of the ankle sending the mpg anywhere from 18 to 180.

2.1 Use the range indicator directly. Now in my case this was reading 55miles when the fuel light went on ,which seems a rather mean estimate when you look at the above figures. Bear in mind i dont drive like a nutter nor do i get stuck in many jams. When i got back it was reading 15 so you can see why i bottled it, at least it seemed to get the 40miles id done right.

2.2 Use the average mpg indicator and your brain. Again dont know how well i can trust this. I got an average of about 47mpg, again seems a bit low to me considering the route and manner of my driving, but ho hum. So in theory for 7 litres, that would mean i should have ~87miles left and therefore still have 47miles left when i got back (not 15).

So there you go (well done by the way if you managed to read this far without gnawing your own elbow off ) What do you all think?

That said...where do you think the digital display gets it's value from? Suspect it's from the same (analogue) sensor as where the fuel gauge gets it's reading from, so neither will be any more accurate...

Rob.

dgital is not conclusive but s far more accurate especially when coming to the end of the tank..

I have an idea....just fill the Fudger!

dgital is not conclusive but s far more accurate especially when coming to the end of the tank..

But if the value for the digital reading is coming from the same source as the analogue reading, how is it going to be more accurate? Especially as an analogue needle (on the fuel gauge) can indicate *exactly* how much is left, whereas the digital display will always have a degree of rounding error to it...

I have an idea....just fill the Fudger!

Am inclined to agree...

Rob.

The range is worked out from fuel left in the tank,not worked of the gauge itself but the tank sender which is still a variable resistor and your ave MPG

It isnt calibrated as such as far as i know so is only a 'rough' guide at best.

lol all im trying to know is how far i can push the tank before refilling. if ive still got 80 miles in the tank rather than 30 then it seems inefficient to refuel.

All its down to is what do i trust, the av mpg reading and the 7 litres which i know are in the tank.

Or the range reading, which must be based on mpg and tank level.

Or neither and just pick one of the 3 official figures from the top.

Its just something which i was wondering about. thats all

The range is worked out from fuel left in the tank,not worked of the gauge itself but the tank sender which is still a variable resistor and your ave MPG

That's what I was trying to get at...

Rob.

All its down to is what do i trust, the av mpg reading and the 7 litres which i know are in the tank.

The trouble with working with averages is that it'll be over a long period of time - so if you've managed 60mpg, your warning light comes on and you start ragging it, chances are you'll only be achieving 20mpg - but your average will probably display somewhere between 40mpg and 60mpg. So you'll run out of fuel in around half the distance you expected...

Personally, I'd trust the fuel gauge and refuel when it's in the red - it's more efficient to fill up too soon rather than too late!

Rob.

What is ineffecient about refilling your tank when you still have some left in it?

Your still spending the same amount on fuel, same amount goes into the engine and a tank holds 50 litres or whatever, so whats the difference?

There is a trade off. Fill the tank and lug around 45kg of fuel or have an almost empty tank into which you get water condensation.

Practically, if you need to make a detour, get stuck in a 3 hour traffic jam (it's happened to me) or need to go to the (e.g.)hospital in a hurry then you don't want to be worrying about the fuel available. Keep it full.

V

As a full tank can give between 400 and 600 miles , i go for the keep it alt least quarter full , that way 100/150 miles in case of emergency trip or stuck too long in jam .Never been one for getting down to the bottom of tank , after ending up stuck on the M3 at 5 AM with no fuel some years ago .

As a full tank can give between 400 and 600 miles , i go for the keep it alt least quarter full , that way 100/150 miles in case of emergency trip or stuck too long in jam .Never been one for getting down to the bottom of tank , after ending up stuck on the M3 at 5 AM with no fuel some years ago .

400 is the most I've ever got from a tank in the Furby. I've not tried using the expansion tank yet though.

Warmer weather should help that one I hope.

In terms of the remaining fuel, the trip computer is optimistic at best and so when the light comes on and it beeps at me, the fact that it says there's 75 miles left in the tank actually means about 30 miles IMO. As above, you never know what's coming such as emergency journeys etc so ALWAYS keep enough fuel in it.

Had an incident a few months back where we needed to scream to the vets fairly late at night. Sooo glad I had 3/4 of a tank in that time. A trip to the petrol station could have meant we would've gotten to the vets too late..... :eek:

The fuel economy figures are for a fully warmed up and ready to go engine. Any cold starts and warm ups will have an impact IMO of 10-15 miles range.

I only let mine get really low once, it took 44 litres to fill up

Normal I re-fill at 36-38 litres.

J.

cheers for the replies.

to be honest i didnt want to turn this into a debate over whether you should or shouldnt refuel before or after the fuel light comes on. It was just a hypothetical question over the accuracy of the digital instruments we have at our disposal.

7 litres is quite a large reserve and with the fuel economy you can get out the skoda, it could be worth a fair few miles.

doesnt matter anyway, im sure ill find out through experience (ive only had the car a few weeks).

It was just a hypothetical question over the accuracy of the digital instruments we have at our disposal.

"Not great". It has been known to be able to drive about 40 miles with the needle at empty and the range at 0...though obviously trying to replicate this is at your own risk...

Rob.

hmmm is the cost of a new fuel filter worth it for experiments sake lol. I could test it the next time and run it till its juddering! Take a jerry can with me.

I could test it the next time and run it till its juddering!

Do it in the name if science

My fuel light came on at 65miles left remaining the other day, I drove another 25 miles and it still said 65miles left

I used to fill my Octavia vRS when the range was flicking between 10 and 0 , depending on how much of a hoofing I was giving her at the time!