The great fuel consumption poll

[TheRapidRooster]

Originally Posted by NigelDay

In the 'grand scheme of things', if you only do 8-9k per year, does it matter whether you get 30mpg or 40mpg ? Do the maths. 200 gallons vs. 267 gallons. Around £400 difference. Just a thought.

Hi Nigel. In the greater scheme of things - as you put it £400.00 on a fixed income can be a lot of money and could be the difference between heating a bungalow properly and skimping on the heating.

There is also another point to consider long before one strays to calculate ones fuel consumption - is it taken from the OBC or is it manually calculated by using the conversion of 4.5461 litres per gallon ?

An OBC that is reading as wild as 17.5% to 20% is going to really put a hole in ones finances and also ones aspirations.

[NigelDay]

I am a meticulous 'brim-to-brim' with fuel consumption. Now at 45k in a D4 FWD manual. Best true consumption (on a tank) is 50mpg, and the worst just above 40mpg. The OBC is always optimistic by 5% (typical range 3% to 7%). On long steady motorway runs in the summer I have seen the consumption as good as 54mpg (70mph indicated, 67mph by GPS). I can't comment on petrol engines having not driven one since 1997.

[RoyMacDonald]

Originally Posted by NigelDay

I am a meticulous 'brim-to-brim' with fuel consumption. Now at 45k in a D4 FWD manual. Best true consumption (on a tank) is 50mpg, and the worst just above 40mpg. The OBC is always optimistic by 5% (typical range 3% to 7%). On long steady motorway runs in the summer I have seen the consumption as good as 54mpg (70mph indicated, 67mph by GPS). I can't comment on petrol engines having not driven one since 1997.

How do you find out how accurately the garage pump is calibrated?

Just kidding.

Roy

[NigelDay]

Originally Posted by RoyMacDonald

How do you find out how accurately the garage pump is calibrated?

Just kidding.

Roy

Well the 'calibration' is supposed to be valid for 15 degrees C (I think).
I could take along some 'laboratory calibrated glassware', but then I could be rightly accused of filing into an unapproved container.

[RoyMacDonald]

Originally Posted by NigelDay

Well the 'calibration' is supposed to be valid for 15 degrees C (I think).
I could take along some 'laboratory calibrated glassware', but then I could be rightly accused of filing into an unapproved container.

A search on the web revels...

When we fill up a Boeing 747, we always use kilograms as the weight of the fuel is directly proportional to the calorific value, not the volume in litres.

The specific gravity is quoted on the fuel receipt and it varies from around 0.78 to 0.81 depending on temperature, so a 3-4% variance quite possible, mostly a function of temperature. Cold fuel sold in litres is going to be better value for money!

TS and the local Petroleum Officer are VERY stringent on calibration checks, however extremes of temperatures can have some affect on accuracy but this is accepted by the authorities.

i had a similar problem, had a focus and was filling it every week, cant remember the figures but sat 50 litres, one day at the pump it did not feel like the petrol was flowing, the car that day held 60 litres, i went into the shop to say it was impossible. they said it wasnt etc, i left my name address etc but refused to pay, it turned out there was a air leak into the petrol pipe in the pump and the petrol instead of been at the nozzle as it entered my car it was underground in the tank
so i put about 10 litres of air in my tank prior to getting the petrol.
i asked the garage for the latest calibration certificate for the pump. eventually the owner settled for the amount i had been putting in for the previous 50 weeks!
sorry to be so long winded, but you might be right!!!!

Trading Standards officers have reported discrepancies at four of 38 sites in Cumbria and 11 of 216 nozzles in Derby. In Newport, just two of 353 nozzles failed – one of them giving more fuel than indicated. In North Lanarkshire, petrol station operators called in Trading Standards last month to help reassure customers that they are getting their money’s worth from the pumps.


An EU ruling that will eventually force retailers to upgrade forecourt equipment to meet the new Measuring Instruments Directive, coming into force by the end of October 2016, has created an incompatibility problem for forecourts with a mix of ageing and newer pumps.

In November, retailers complained of having to put up with older pumps over-dispensing fuel until they can be replaced completely. Meanwhile, with drivers ever-wary of being ripped off at the pump, the chance of a visit from Trading Standards grows.

Guess to check the cars readout for accuracy we would need to know the temperature that was used during calibration. Also how worn your tyres are as well. Also the calorific value of the fuel and the temperature it was dispensed at and how the garage pump calibration had been set.
Roy

[NigelDay]

I did think about weighing a can of '10 litres' of diesel, but I think Mrs D would have me sectioned. She already complains when I weigh liquids in the kitchen (she would use a less precise graduated jug).

[RoyMacDonald]

Originally Posted by NigelDay

I did think about weighing a can of '10 litres' of diesel, but I think Mrs D would have me sectioned. She already complains when I weigh liquids in the kitchen (she would use a less precise graduated jug).

If you have a decent set of bathroom scales you could use those. Weigh yourself holding the can and not holding it. I have some high tec German ones that are always accurate.

Roy

[bobby2000]

Originally Posted by RoyMacDonald

If you have a decent set of bathroom scales you could use those. Weigh yourself holding the can and not holding it. I have some high tec German ones that are always accurate.

Roy

Why not just put the can on the scales.

[TheRapidRooster]

Hi to you all If it is any help :--

The weight of a litre of diesel is 0.8508kgs - making 1 gallon 3.8678kgs

The weight of 1 litre of petrol is 0.7327kgs - making 1 gallon 3.3330kgs.


The info for the petrol weight came from Shell UK after a phone call some years ago.

The weight of the diesel came off of a Google search.

[iana]

Can anyone give me an idea of what mpg I will get from a 2.0 D4 FWD geartronic XC60, the car is on order and Im expecting delivery in March, just getting puzzled as there seems to be vast difference in mpg being obtained - I was sort of hoping for early to mid 40s, the journeys will be normally on B roads with the occasional motorway run