What's your car's BTU per Mile?

EUGENE, Ore. (AP) -- A Eugene woman has filed a federal lawsuit alleging that major oil companies are chiseling motorists by selling overly warm fuel that delivers less energy than it should.

The premise of the lawsuit and those filed in several other states is that as gasoline and diesel fuel warm, they take up more room in tanks and deliver less energy per gallon.

The suit filed by Shonna Butler, a university fiscal analyst, says that a gallon of gasoline at 60 degrees Fahrenheit, the government standard, has a volume of 231 cubic inches, but at 90 degrees, the same quantity of gasoline is nearly five cubic inches larger.

I believe the point they are making is that a gallon of gas at a warmer temperature doesn’t provide the same amount of energy that a cooler gallon of gas will because fuel expands therfore even thou you get a U.S. Gallon of fuel, it isn't as dense in the summer as it is in the winter, so it won't burn the same.

According to what I have read if they were selling the gas at 100 degrees that difference would only amount to around 3% BTUs less. But the same can be said if the fuel is pumped in cooler temperatures (under 60) like around 20 degrees then you get a 3% BTUs increase. So depending on where you live you get a better deal than people who live in warmer climates.

Also, when that gallon then gets in your tank wouldn't there be a huge swing in temperature as well.

Plus what consumer is going to drive up to a pump and see that this fuel is sitting at 70 degrees so it will only provide 50BTU, then get in his car, go to the next one that is sitting at 60 degrees and it says it will provide 51BTU per gallon. We all look and say hey it’s 2 cents less a GALLON at this station.

But I guess I was under the illusion that we were paying for a U.S. Gallon of gas not a certain number of BTUs. Well according to the OOIDA (below) we should be buying our gas by the BTU.

So as the fuel warms then the pump can’t compensate for the temperature change. So in the sumer the pump could say it pumped a gallon and really you only got 99% of a 60 degree standard gallon at 80 degrees or only 97% at 100 degrees. That is a problem but isn't the state testing the pump, and those tests happen at various temperatures at various times of the year when the pump is calibrated. So when you pull up should you be looking to see if your pump was calibrated in December or July? And I can't think of a time that I picked up the nozzle of the pump and thought "Wow, this is burning the hell out of my hand!". Most of the time every thing is pretty cool to the touch so I can't believe that the fuel is coming out at some extreme temperatures.

I think growing up I had heard a few times that it is always better to fill up in the mornings then in the middle of the day but with the large amount of fuel in the ground, and how much fuel some stations go thru I can't see how that would make that much difference.

So at today’s prices a person with a 20 U.S. Gallon fuel tank could be losing about $20 over the course of the summer if the fuel was being pumped out at 100 degrees all summer. At 80 degrees fuel temperature you would be getting about 1% less energy so over the course of the summer you would be losing about $7. (20 gallons x 12 weeks x .01 x $2.70 per gallon)

Now if they prove that the Gas station is actually WARMING the fuel on purpose and that the pump then doesn’t pump right, then I can see why we should be up in arms, otherwise it just doesn’t sound enough to justify some huge amount of legislation. One estimate is that it would cost between $2 and $4 Billion to retrofit all of the gas stations in the country. Other estimates I have seen are much higher. But even at the lower numbers, who do you think is really going to pay for that retrofit? The consumer gets to pay for the upgrade. Would we really see more money in our pocket after a couple of years of having temperature-compensated sales? Some how I doubt it.


From: Owner-Operator Independent Drivers Association

When a petroleum product expands and contracts with temperature, there is a corresponding change in the energy capacity of a gallon of that product, as measured in British Thermal Units (Btu). Warm fuel will produce less Btus per gallon, and cool fuel will produce more Btus per gallon. Retailers buy and pay for wholesale fuel that has been temperature-compensated to 60 degrees F where its Btu rating is what is advertised on the pump. However, if retailers sell fuel that is warmer than 60 degrees F, the consumer is receiving less energy capacity per gallon than is labeled on the pump

All digital retail pumps currently manufactured in the United States, and in-service nationwide, have the capability of dispensing temperature-compensated fuels. That function, however, is currently not being used.

It is argued that with temperature compensation, the consumer will rarely receive an actual gallon of fuel. This is meant to scare consumers. Consumers will receive equivalent BTUs per gallon with temperature compensation, and can shop by price. (per BTU I guess)

Some people argue that since fuels and fuel blends have different BTU values, and there are seasonal differences, temperature compensation cannot deliver the same BTUs every fill-up. This is an apples and oranges argument. On any given intersection, consumers will be able to shop, by price, for the same labeled product, knowing all the gallons have equivalent BTU values. (The image I get from this is old people just standing there with a 1000 yard stare, looking at the pump trying to figure out how many BTUs they need.)

The one-time cost to retro-fit retail pumps is very close to the extra amount consumers already pay annually for hot fuel.