Why is it reccommended to fill up your gas tank after sunset?

jibbers is correct. It's to minimize smog formation which requires heat as one of it's elements to form. Filling in the evening, will allow the fumes to disipate.

I've never heard that, but I guess the theory is that the fuel will be cooler and there for more condensed. So in the morning, when the air warms, you magically get more fuel in the tank as it heats and expands. I'm not a math or chemistry whiz, but it seems to me that it would take more than a sun set to cool the thousands of gallons in the stations tanks enough to make a difference. You MIGHT get an extra ounce during the day, but remember, on that theory, when the sun sets, you're tank will lose fuel too. So you're really getting nothing special.

Because it is cooler, the best time is early morning, gas and fuel, like metal , will expand when it gets warmer outside. Filling up your tank late in the day, when it cools overnight, it will seem like you have less gas.

Partly due to air polution.

You will also GET MORE GAS by allowing the tank to fill slowly as the fumes pushed out of the tank evaporate. No one benifits but the gas companies.

WILL SOMEONE TELL MR. BUSH ENOUGH IS ENOUGH.! We know he is the cause of high prices...................

i've heard u should fill up early in the morning, gas prices haven't gone up for the day yet

Check out the big brain on jibbers4204! She gets the best answer on this one. Does anybody know, is she single. I just love smart women!

to protect the ozone! When the sun is out there is more ozone in the air. That's what i was told???

I have never heard that.