How accurate is your petrol station?

[The Natural Philosopher]

Our Freelander JUST popped its little yellow light on, so we drive to the petrol station and I put 63 liters of diesel in.

I then spent ten minutes to find in the handbook that the usable capacity of the tank is 59 liters. 4 liters in 59 is equivalent to an over charge of 6p a liter. And it was by no means empty either.

Its not the first time I have manged to put more fuel in a car than the handbook says is the tank capacity, in fact since I always run my cars to the limit and fill them full, I'd say it was more often than not.

So has anyone a reasonable explanation other than that the stations simply set their pumps low..? how much are they allowed by way of inaccuracy? how much are the checked, and by whom?

I'd be interested to see if my experience is actually widespread, or as I suspect, actually endemic.

So called 'cheap petrol' may actually be 10% more expensive than you think...

[Clive George]

The car manufacturers set their tank sizes low.

IIRC petrol stations are checked quite strictly.

cheers, clive

[Dave Fawthrop]

|Our Freelander JUST popped its little yellow light on, so we drive to |the petrol station and I put 63 liters of diesel in. | |I then spent ten minutes to find in the handbook that the usable |capacity of the tank is 59 liters. 4 liters in 59 is equivalent to an |over charge of 6p a liter. And it was by no means empty either. | |Its not the first time I have manged to put more fuel in a car than the |handbook says is the tank capacity, in fact since I always run my cars |to the limit and fill them full, I'd say it was more often than not. | |So has anyone a reasonable explanation other than that the stations |simply set their pumps low..? how much are they allowed by way of |inaccuracy? how much are the checked, and by whom? | |I'd be interested to see if my experience is actually widespread, or as |I suspect, actually endemic. | | |So called 'cheap petrol' may actually be 10% more expensive than you |think...

The pump is a hell of a lot more accurate than your calculations and the supposed capacity of your tank.

I have watched with interest as Weights and Measures, or some such organisation measured the accuracy of a pump using a traditional brass bound tub as a measure.

Using inaccurate scales or pumps when selling to the public gets you prosecuted.

[Andy Hall]

This might be a Land Rover thing.

If my Discovery is down to the fumes, I can squeeze 90 litres of diesel into it. IIRC, spec. is 80 litres.

Either way, it doesn't matter because the fuel is metered by the pump. You pay for what is delivered.

[EricP]

Petrol is subject to the same regulations as pub drinks. A pint means a pint a gallon a gallon and litre, exactly one litre as officially stipulated, no more or no less.

It is a serious offence to under or over sell.

If in doubt, contact your local weights and measures dept which comes under the DTI.

[Dave Plowman (News)]

IIRC, they're checked regularly by customs and excise. And if they found more than one pump wildly out in the garage's favour would smell a rat.

I've never managed to put more fuel in than I'd expect - and I always run the tank down until the warning light comes on - then fill to the brim. I also log the amount of fuel bought and it agrees with the OBC on the car.

Dunno about 'cheap petrol' - I use Tesco as it's the most convenient.

[Clive George]

Of course there's the common practice of underselling of beer by including the head in the price :-(

cheers, clive

[Fred]

Trading standards gave up checking petrol stations years ago. I doubt there are any checks made at all these days unless there is a suspicion something's amiss.

[John Rumm]

I have heard the suggestion that there is a small tolerance specified for the delivery of the petrol, but modern pumps are so accurate that they can be set to deliver consistently less than the quoted amount but still within the allowable tolerance. Whether that is true of just hearsay I have no idea.

(I have also seen the weighs and measure people testing the local station - so testing does happen)

[Andy]

I believe the accuracy demanded is +/-3%. I did hear one garage was prosecuted because all its pumps came in at something like -2.9%! They had been deliberately set low, so there must be more to the law than a straight

+/-3% suggests else they'd have gotten away with it. My experience is that the average petrol stations achieves even better than that, as I too always run my tank down to nothing and a 10% error would be very noticeable. I reckon +/- 1% is more like it.

Andy.

[Chris J Dixon]

Andy wrote:.

There are a couple of points about filling tanks. Firstly many manufacturers caution against filling "brim full" as they design the tanks to have a certain amount of air space. Secondly, the amount of trapped air and the trigger point of the auto-shut-off can vary with the speed of delivery.

I do recall, some years ago, a pump with a small mechanical counter on one side, which appeared to relate to the total volume dispensed. Adjacent to it was printed a multiplication factor which was close to, but less than 1.

Chris

[Vortex]

Well this

seems to be the "standard".

The graph on page 13 indicated the spec is +/- 0.5%

David

[Ron Lowe]

Not so, I saw our local petrol station being checked a few months ago. I'd never seen this before, so I watched with interest.

They were filling stainless steel containers with a scale scribed on a perspex window up one side, and then pouring the fuel back into the station's fill points.

I'm not sure which agency it was, I think a local council agency rather than a national one.

Also, on my way back home travelling north from Manchester Airport last week ( Week sailing in Turkey:-)) , I stopped at a service station to fill the car's tank and drain the kid's ones. I noticed the pumps had recent-looking stickers proclaiming that the pump had been checked for accuracy by some local authority ( Cumbria, or somesuch.. )

[Dave Liquorice]

Aye, the local trading standards office *will* go a check if given a tip off.

Only with brim glasses... I rarely drink in a pub thses days but aren't the majority of glasses now lined? Anyway there is always the:

Can you fit a double whiskey in there? Yes. Well top it up then.

[Guy King]

The message from The Natural Philosopher contains these words:

Every car I've ever had has been capable of taking more than the stated tank capacity. Trading Standards check dispensing accuracy frequently, so I guess it's the manufacturers being pessimistic.

[Guy King]

The message from "Clive George" contains these words:

Some glasses have a line scribed on them to show where the liquid level should be.

[Guy King]

The message from "Fred" contains these words:

I saw Tescos being done a year or so ago, though I don't know if it was an internal thing or statutory.

[Brian Sharrock]

It's, at best, orthogonal to the subject of fuel-pump accuracy; but I was rather astonished one morning while at the check-out in a large supermarket-chain to witness a supervisor going from check-out to check-out: she 'punched in' a code then placed a one-Kg weight on to the weighing scale and received a print out from the till. Apparently this was a 'record' for the weighing scale and was a 'daily' activity. A TSO told me that this was a requirement - but seemed unphased when I queried the difference between a point-reading and the slope of the readings, [ 1Kg may read as 1 Kg, but what does .05 Kg and 5Kg read?]

BTW; I decided to go with the flow; ... and not pursue the matter.]

[Derek ^]

My car was bought at a big discount from an internet personal importing agent. The car was perfect and had been PDI'd the salesman just warned me that the only thing he couldn't do was put fuel in the car and advised me to go to a Tesco 300 yds away for fuel. About 50 yards to go the car started spitting/misfiring and I made it to the pump only just. It took 72 litres to fill the tank. The red light came on the next time and it took 62 litres to refill the tank.

Long and short is I know how much fuel it takes to fill the tank at the instant the red light comes on, and how much of the remaining 10 litres I've used. In 4 years it has never been as much as a litre out.

DG

[Staffbull]

yep, my V70 used to take about 8-10 litres over its alleged tank size and empty it rather rapidly!! but not as rapidly as our V8 Discovery :-(