Gas pumps and a potential scam

[In America]
While pumping gas recently I noticed that if you pump your gas slowly by lightly squeezing the nozzle on the gas pump there is a point at which you can see the “gallons” meter move with out the price changing. As if you are getting a few hundreths of gas for free. Seems to happen every few cents and rather consistently.

Now this concerns me. Is this a way that the gas companies (stations?) can shave a little more out of us? (one scam is the $1.599/gallon = $1.60/gallon) Since I found this I have made it a point to squeeze every little bit I could out of the gas pump in thinking that over time I was saving money which I realize is very small on my own personal scale. But what about the teemings who dont do this? This would add up to a considerable sum over time multiplied by thousands of daily fuelings that gets pockets by someone else?

any thoughts on this?

I proofread the post I swear!

“few hundreths of gas for free” should read “few hundreths of gallons of gas for free”

If I understood you, the gas continues to flow, but you’re not getting charged for all of it. It doesn’t sound like the gas station operator is scamming.


I owned a chain of gas stations for a number of years…

Gas pumps (or, more accurately gas dispensers) are tested and sealed by local weights & measures authorities regularly. Your risking jail as well as the loss of your business by trying to “shave” any meaningful amount.

That being said, when you squeeze out your extra hundreth of a gallon all thats occuring is that the next customer rings up his first penny a hundreth of a gallon sooner. (And your most likely looking at the 3rd decimal place which is actually a thousandth of a gallon…)

I doubt a scam is in place. There is simply a limit to how precise the measurment of gas can be and the price affixed to that amount. Gas pumps calculate to the thousandths of a percent. If the pumps use typical rounding rules that would mean you get charged an extra cent if you pump $0.005 of gas. If you manage $0.004 then you get ‘free’ gas. I put ‘free’ in quotes because if this is significant to the gas companies or station owners they have likely figured it in to their pricing scheme and cover that loss with a slightly higher pump price. $0.004 worth of gas is not much (I bet it costs more to just start your engine) and fiddling trying to get that teeny bit will probably cause you to overshoot and end up buying more gas anyway which is just fine with the station owner.

Surely all you’re doing is getting the maximum amount of gas the pump allows for the given price?

And surely when the next person comes along the pump re-sets itself anyway so they dont lose out if you’ve squeezed out your money’sworth.


See what Iam afraid of is if everyone does not do this then we are all getting less than what we paid for and that adds up to quite a loss over all.

Surely you have better things to do than worry about squeezing that extra penny out of a purchase. I am constantly amazed at the lengths to which people will go for a measly freakin’ penny.

I have a 5 gallon jar of them which you are more than welcome to if you are willing to pay for the shipping…

Perhaps its not a scam but a flaw or mechanical error then?

You are right I am looking at thousandth of a gallon per turn for me so I never really amount to any individual savings but… (See my previous post)

Its not about the penny for me or even the .001 of a penny its about how it adds up to a cumalative loss for everyone over time for everyone else…

Or maybe the few who do it get a trifle more than they paid for.

Businesses the size of oil/gas companies don’t calculate their pricing on each individual transaction and its niggling details. They look at the big picture. If everyone starts doing what you described, and it results in more gas being dispensed without corresponding income, their solution will be to raise the price. That would also add up to “quite a loss over all.”

If you feel it’s worth the time and trouble you spend to save your penny, go for it. But as for making it a crusade for everyone to do it, well…A) most folks probably won’t feel it’s worth their time and trouble, and B) in the long run, nothing will be gained. It’s not like this is free gas for the taking. It was bought by those who provided it to you, and it will be paid for by consumers, one way or another.

This thread reminded me of a fictional pump scam I read about in an RPG sourcebook (White Wolf - those who’re interested in this system probably know of it already). It claimed that authorities only checked the accuracy of gas meters at certain fixed, knowable intervals (like at 1/4 of a gallon, 1/2 a gallon, whatever). Thus a device was invented that would shortchange the customer in such a way that it would check out ONLY at the intervals being tested for.

Of course, I’m sure there’s a reason this wouldn’t work IRL, and I probably miscommunicated how the device purportedly worked (can’t find the book - probably in storage), but that’s what I thought of…

Just so I’m clear, the OP is concerned that gas stations might be “intentionally” overcharging customers by about .04% on a $25 fill due to rounding errors unless they go to the effort of squeezing out the last couple drops of gas? Do I have that right?

Leaper, I believe that system has been used IRL. It is not complicated. Suppose the standard testing is for an integer number of gallons. All you have to do is subtract from the first half of the gallon and add to the second half in the same proportion.

Gas dispensers are programmed and if you can change the programming you can do pretty much anything. Knowing the inspectors only come during certain hours you could shortchange customers only at other hours, etc.

If you know the inspectors only check for small amounts, like 1 or 2 gallons, you could cheat only in higher amounts. Etc.

I don’t know if this is something of a scam or not. When you pre-pay for a certain amount of gas/petrol, many pumps will slow down ten cents before the total pre-pay amount. Increasingly, I’ve seen that slow-down get even slower, where it takes about a minute to pump ten cents of gas. I’ve also seen the slowdown occur at 20¢ or 25¢ before the total pre-pay amount is reached.

Must be so they can cut it off at exactly the right moment mate.

Is there any BS with the Octane levels? I have heard (which could be complete BS) that it is not uncommon for a 91 high octane gas supply to be ‘accidentally’ contaminated with some 87 octane gas due to a ‘screw up’ when the trcuk came to refill the gas.

Obviously the implication is that the station pays less for the gas but sells it at a premium.

ChryslerBldg, any truth to that in your experience? Are the weights and measures people just checking the volume, or the octane of the gas as well?

Yarster, I doubt octane scams can really happen with some of the larger companies. My vehicle requires 91 minimum. I would know if I filled it with 87 due to heavy knock, about 20 HP less power and other difficulties. I would have the gas tested (well, I’m sure Toyota would since it’s under warrenty) and because I keep all my receipts it would get detected rather quickly (and I’d sue the pants off of them for damage).

Basically what I’m thinking is true scams probably would be detected because of the shear number of people buying gas. I like to calculate my mileage and although I won’t notice a few cents, I’d certainly notice $5.

When the pump cuts off, is there any residual left in the line? I’ve seen people raise the hose, to drain everything in the hose into their tank. Does that work?

I was thinking the pump is slowed down to a crawl, much slower than in the past, so the pumper would get frustrated with waiting 30 seconds to pump those last few milliters, and ultimately decide to stop early. The result - someone buys $10 in gas and pumps only $9.90. With an already low margin on gasoline sales, those few extra cents would increase the profit from gasoline sales quite a bit.