Petrol Density vs Mileage

Yes. Density increases as temperature decreases, as it does with all fluids.

Or, volume decreases. As the fluid warms, it expands.

Many if not most fuel station tanks are buried. There is little day/night temperature change, but there might be seasonal differences.

sort of, yeshttp://www.snopes.com/inboxer/household/gastips.asp

Well, maybe, but...........................

I think that, at least here in the good ole US of A, where politicians are for sale to the highest bidder, if there's a way to screw the consumer it will be done.

That said, even here in Arizona, where business is king, I can't see much impact.

But, at the pump, the volume dispensed will vary.

Does that mean less energy density in the tank, as it expands?

Automatic Temperature Compensation | Tokheim says this:

"The science behind the technology

• Let's take an example of a tank with an average annual temperature of 11.6°C.
• The temperature co-efficient of fuel is 0.1% per 1°C of temperature change. This means that every time the temperature of the fuel increases/decreases by 1°C it expands/contracts by 0.1%.
• European legislation allows you to dispense fuel at 15°C.So, your service station would save 0.34%* annually in fuel volume (*predicted saving based on 15°C -11.6°C= 3.4°C multiplied by 0.001)
• A small service station selling 2.5 million litres of fuel per year would save 8,500 litres of fuel
• With the rising cost of fuel, that's potentially €15,000 per annum."

Or, you could shut the pump off, and then squeeze the gas pump nozzle into the tank one more time to relieve the pressure in the hose so that as the flexible hose contracts, that amount of fuel will go into your tank. The next person will then have to pay to pressurize the hose.

I'm confused by that!

It assumes the fuel is delivered by tanker at 11.6°C. Assuming it is metered by volume, and the service station has no control over temperature, if it's delivered colder they makes more money if it's lower (and vice versa), if they sell at 15°.

But selling it at 15° is extra profit for the service station, so there's no way they will voluntarily install ATC, assuming temperature rises during storage, as implied by Tokheim.

Example given comes to €6 per m³. My estimate of cost to warm it 3.6° is only about 20 €cent/m³, so it would be worth doing it (as long as no ATC in place).

And how is the fuel delivered to the service station. In nice shinny metal truck. Driving for how long in the nice bright sun? So the fuel will be hotter than when it left the tank farm that loaded the truck. As the fuel expands, the truck now has more gallons of fuel than when it left the loading point. As it is dumped into the underground storage tanks at the service station, it will cool off again, so the service station now has less gallons of fuel to sell.

So please leave a few extra dollars for the poor starving service station owner that is going broke selling you fuel.

In 2nd world countries petrol is often sold from above ground tanks. these can expose the contents to the sun and the fuel temperature can vary, especially in small tanks. Warm fuel is less dense than cool fuel, will have less moles per liter of the contents.

In first world countries the tanks are located underground as required by zoning regulations, and the temperature of the fuel does not vary. Summer and winter fuel are manufactured with different formulas in the USA, with winter fuel having more volatile compounds.