It's road trip season, so you might be pumping a little more gasoline than normal. One viewer wants to know, in the heat of the day, are you getting less fuel when you fill up?

“Does outside temperature impact my experience at a gas pump? Our family would like to know so we can make the most of our trips, here,” asked viewer Chase Ezell.

When it's hot are you getting less fuel at the pump? For answers, we're looking at a study by Consumer Reports, talking to a PhD scientist at the University of Texas Energy Institute, and starting with middle school science.

Remember, heat makes liquids expand into gases. And gases are less dense then liquids.

So, an expanded gallon of fuel would have less energy inside.

“During the heat of the day, if I fill up with fuel am I getting less fuel?” I asked Dr. Joshua Rhodes.

“Not really because it depends on the temperature of the gas itself. Since the gas is stored in an underground tank, it’s not going to experience those temperature increases that we do outside,” said Rhodes.

What he's saying is that underground temperatures are cooler and fluctuate much less than air temperatures.

In 2008, Consumer Reports looked at this issue. It found that fuel that's been sitting inside the pump dispenser can be warmer, because it's hit by sun.

But that warm gas only expands by 1 percent, so the effect is negligible. And that's just the first few gallons sitting in the dispenser. The rest of the fuel is cooler because it’s been stored underground.

So, when it's hot are you getting less fuel? The answer is no. The effects of the heat are too small.

However, on ozone alert days, the EPA recommends not filling up in the heat of the day because you're releasing gasoline vapors -- and that contributes to ozone formation.

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