1.4 VW Polo. Fuel consump w/ full tank?

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Wed 18 Jul 2007 10:36
1.4 VW Polo. Fuel consump w/ full tank? - shirike
Car is 96 N VW Polo 1390cc. {Edited in by DD}

I filled my tank right to the limit yesterday before work. After finishing work I came back to my car and the tank was still showing as full or the closest thing to it (it's only a couple of miles from garage to work so I wasn't expecting any major consumption).

However, after driving home (via Pulman's) and then back to work this morning I've suddenly realised that the needle is between the 3/4 and full marks!
I always reset the trip odometer when I've filled my tank and it shows I've done 18.2 miles.

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However, last time, the efficiency seemed fine between 3/4 and 1/4 tank - is there any reason a car will run very inefficient with a full tank?

Could it be the sensor in the tank reporting a false level? Would a leak behave this way? I'm wondering if there's a leak which only happens when the tank is full?
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Wed 18 Jul 2007 10:38
Fuel consumption w/ full tank? - shirike
Car is 96 N VW Polo 1390cc. {added into thread where necessary - DD}
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Wed 18 Jul 2007 11:16
Fuel consumption w/ full tank? - GregSwain
Sounds like the gauge is being inaccurate - the consumption should certainly not be worse just because you've got more petrol in the tank!

To work out your fuel consumption to see if there's a leak etc....
1) Fill to the brim with fuel & reset trip meter
2) When it's getting low, fill to the brim again and get a proper receipt from the petrol station showing how many litres you've put in. Note your trip mileage on the receipt too.
3) Divide the trip miles by the litres of fuel to give a "miles per litre" figure. Multiply this figure by 4.5 to get MPG.

Personally don't think you'll find anything untoward, but it's always nice to know what MPG you're getting.
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Wed 18 Jul 2007 11:41
Fuel consumption w/ full tank? - shirike
I'll give that a try, thanks :D

Bit scared of letting it run low though - I'll have to get a petrol can in the boot in case I conk out :D
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