I filled my Peugeot 107 up to the brim with petrol yesterday to the drive a 160 mile journey taking 3.45 hours. Very pleased to see that only 1 bar on the gage had been used??? I had the air con on for the last 1.5 hours of the journey. How could I have used so little petrol? Can I trust my petrol gage? Could it be that the journey was on very flat terrain? I didn't do any heavy breaking or acceleration. I'm quite puzzled about it. Happy but puzzled.
Fuel gage confusion
- Thread starter 32tybeams
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Try looking at the gauge again in the morning......
John
John
Seems to be a common feature of modern fuel gauges. They are totally non linear. The first bit goes down really slowly, half full on the gauge is about one third full, then the last bit goes down really quickly. Still haven't worked out why but lots do it. It can't be hard to make them accurate so it must be deliberate.
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I guess he means the digital one like this, so 6 bars...
OP, only having one bar missing could easily mean that the 2nd bar is just about to vanish. Sou you could well have used just shy of a third of a tank, really.
The 107 only has a 35 litre tank, so one sixth of a tank (ie first bar only just went out) is 5.83 litres, whilst one third would be 11.66 litres.
For your 160 mile journey, that's a range from 125 mpg to 62mpg, 62 being easily do-able in a light small car with plenty of cruising.
Agree, but I find, rather than your curved graph of how the gauge goes down, that it's more a case of that they remain stuck on full for 30-50 miles before starting to go down. So not properly linear, I agree, but more kind of offset to the real fuel level.
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A little scam that boat charter companies do is use the fuel gage to tell you its got a full tank and then when you return it they top it up to full and charge you for the difference. The difference between the gage showing full and the tank actually being full can easily be as much as 25 litres. I now always fill up before I leave and keep the receipt.
Thanks for all for your help. The petrol gage shown by Rsgas is the same as mine. The day after the long journey I went on a 28 mile journey. The petrol gage still showing 5 bars. Driving on 60 mph roads. I finished journey with gage still showing the 5 bars.
Referring back to the 160 mile journey (Sheringham to Birmingham). I had done that journey in reverse 4 days before and only used 2 bars. I reckon it's the flat terrain of route and no heavy breaking and acceleration also only me in the car. And I'm a lightweight.
Referring back to the 160 mile journey (Sheringham to Birmingham). I had done that journey in reverse 4 days before and only used 2 bars. I reckon it's the flat terrain of route and no heavy breaking and acceleration also only me in the car. And I'm a lightweight.
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Op
Please note that your fuel and oil are measured by gauges not gages. Hope you don't find this too nit-picking
Please note that your fuel and oil are measured by gauges not gages. Hope you don't find this too nit-picking
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Each bar represents around 6 litres of petrol - maybe one of the bars was just about to go out?
Does your car have a fuel computer? Much more accurate than a fuel gauge any day but as big-all says, brim the tank, drive your journey then brim again. Fuel temperature aside it will be as accurate as you can be.
John
Does your car have a fuel computer? Much more accurate than a fuel gauge any day but as big-all says, brim the tank, drive your journey then brim again. Fuel temperature aside it will be as accurate as you can be.
John
yes to the same level if possible to be as accurately as possibleEach bar represents around 6 litres of petrol - maybe one of the bars was just about to go out?
Does your car have a fuel computer? Much more accurate than a fuel gauge any day but as big-all says, brim the tank, drive your journey then brim again. Fuel temperature aside it will be as accurate as you can be.
John
over longer journeys off perhaps 100miles plus the accuracy off topping up will be virtually 100% accurate as you will be talking perhaps 2% difference with sloppy filling up or careful trickeling in
where as lower levels off use and refilling the tank will give the chance to greater inaccuracies
As everyone else has said, don't use fuel gauges (or even trip computers!) for fuel consumption. Brim the tank and note the mileage, then do your driving, brim it again and subtract your initial mileage from the new mileage when you brimmed the tank. Better still, use one of the many free "apps" (I use fuelio) and do it over several thousand miles. Most car fuel gauges aren't particularly linear.
Fuel gauges used to so much simpler. My 1965 Super Minx had a simple fuel sender unit inside the tank which was connected to the fuel gauge. As the float inside dropped (as fuel levels dropped) the needle moved accordingly.
Only trouble was the needle used to bounce up and down as you went over bumps!
Only trouble was the needle used to bounce up and down as you went over bumps!
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