I Bet You Didn't Know You Are Getting Shortchanged At The Pump?

When you buy a gallon of gas at the service station, you don't always put the same amount of energy in your tank.

Gasoline, like other liquids, expands in high temperatures. Although gas pumps always dispense the same amount, the fuel is less dense when it's warm. That means you spend a little bit more to get the same amount of power for you car.

Consumer advocates say drivers are getting short-changed, particularly in warm-weather states such as California.

"This is a system that is totally rigged to misrepresent how much gas you're getting," said Jaime Court, president of the Foundation for Taxpayer and Consumer Rights.

How much does this cost drivers? A study by the Kansas City Star newspaper, which brought the issue to light, estimated that Californians would save about $450 million if the state's gasoline pumps adjusted for temperature.


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Agent009 - 5/29/2007 3:53:37 PM

+1 Boost

This is a big issue in the sunbelt states where the avg street temp is over 60 degrees 9 to 10 months a year and a profit source for the gas companies.

BMWRocks - 5/29/2007 4:04:55 PM

+1 Boost

This stuff just makes me pissed.

Threepoint1415926 - 5/29/2007 4:29:19 PM

+1 Boost

I dont see how their getting short changed. I can already see the result of pumps that give a more realistic evaluation of the energy you're getting.... Analysts with a new and improved view of how much to charge to make up the difference!

Agent009 - 5/29/2007 4:47:10 PM

+1 Boost

The fuel is measured and volume is constantly adjusted to the 60 degree standard from the refinery to the gas station at every step along the way. They all pay correctly for the fuel since the temperature is taken into account.

But when the tank is filled at 80 degrees the gas has now expanded, and you actually the equivalent to say 19.5 gallons at 60 degrees, but you were charged for 20 gallons.

That extra 1/2 gallon now stays at the gas station ready to be sold literally again..

Threepoint1415926 - 5/29/2007 6:02:20 PM

+1 Boost

I realize this. It's not that I dont understand, what I understand most is simply that the prices are more fluid than the gas itself. Say the customer didnt have to pay for that 1/2 gallon so to not be ripped off. What's to stop a smart gas company from raising the price of gas to take that into account? Hence, my comment about an analyst.

Agent009 - 5/29/2007 10:22:37 PM

+2 Boost

Well don't forget that four basic factors are in play at one time:

1. Increased consumption due to summer vacations creates more more gas sold overall. $$$

2. Increased demand creates higher prices so the gas companies make more $$$

3. Increased temperatures lower mileages due to air conditioning and lower thermal efficiency. $$$

4. Increased temperature maximized the boost in profit per tank due to the failure to compensate for the expansion of the gasoline.

So in a nutshell:

During the summer months cars get the worst mileage causing tanks to be filled more often, the tanks are filled to the least amount possible due to expansion. The prices are raised to the highest levels to compensate for increased demand.

Every way the gas company wins and records record profits.

vdiv - 5/29/2007 4:37:41 PM

+2 Boost

This is nonsense. There are no oxigenates in the summer mix which gives you better gas mileage. The air is also less dense when it's warm so it creates less drag when driving through it. So do lubricants in the drivetrain.

There are a lot of temperature dependent variables that affect fuel economy, but at the end you get better gas mileage in the summer.

Agent009 - 5/29/2007 4:48:46 PM

+1 Boost

Not in my state, the AC is running and you see 1/2 mpg decrease.

Plus the engine power is down so it takes more gas to give the same power so you lose there too.

Basic concepts.

AdmiralT20 - 5/29/2007 4:49:19 PM

+1 Boost

It is a fact that fluids expands with increased temperature.
It is also a standard practice that you calibrate flow meters for temperature and pressure changes.

So, it is correct that the volume of fuel you get at the pump when it is 30 degrees C(86 F) is less than what you will get at 20 degrees C(68 F)

The pumps are supposed to correct for this variation by recalibrating the gauges- but I am afraid they don't do that as frequently as desired.

I used to see the calibration dates and conditions at the pumps before, but now it is a rarity to see one that has the calibration date with the conditions under which the calibration was done.

Till gas stations start implementing standard practices, the recommendation will be to fuel up very early in the morning or late at night.

vdiv - 5/29/2007 5:38:55 PM

+2 Boost

Actually the volume is the same. The weight, or number of hydrocarbon molecules is less.

webguy - 5/29/2007 6:53:30 PM

+1 Boost

Ha! You mean I’m getting the shaft every time I fill up my car? You don’t say?

I’m surprised fuel intake isn’t placed on the bottom of the car, so it forces you to "assume the position" and illustrate exactly what’s happening to you every time you put fuel in the car.

Where I live, it gets 115(F) in the summer fairly regularly. I could protest and ride bike, but I’d die. So… "expanding" gallon+ summer prices + air conditioner = I should at least get a thank you for "assuming the position" note in the mail.

The good news is, I’ve done surpassed the angry psycho-rage a while ago. I’ve reached an ambiguously pleasant state of numbed bliss. News like this is a thick, wafting stench I can’t smell any more; it just hits me like a calm breeze.

WickedRabbit - 5/29/2007 11:37:30 PM

+1 Boost

my uncle recently told me about this maybe a few weeks ago. Said it's best to fill your car at night here in California because of it.

gsh23 - 5/30/2007 12:47:01 AM

+1 Boost

yah i never understood why people bitch and moan about 10 or 20 cent increases in fuel. so its an extra couple bucks everytime. seriously if its a problem with not having enough money, there must be a million other ways of changing your lifestyle to save.