[RedDevil]

While the difference is small, it is not entirely negligible.

https://www.quora.com/How-much-more-dense-is-gasoline-in-50-degree-F-weather-than-it-is-in-80-degree-weather


Seems like 1% for every 8 degrees Celsius.
At least there's some compensation for winter gas being less dense.

Looking up the prices at https://www.eia.gov/petroleum/gasdiesel/ $2.50 seems average in most states.
Let's say with ten gallon at $2.50 a gallon then a hot summer afternoon or chilly morning at 16 degrees less could make a 50 cent difference for the same fuel.
Or get you 0.2 gallon extra for free; that's 12 whole miles at 60 mpg...

When it is cold and you don't plan on driving much after fillup, don't brim it to the neck; it might spill when it expands.

Here in the Netherlands gas goes for €1.66 a liter, that would be about $7.50 a gallon... But most of our filling stations have underground gas tanks and therefore hardly any temperature variation.