What Time of Day Should You Fill Your Gasoline Tank to Save Money?

An estimate 51 million Americans will be traveling the roads this Thanksgiving, AAA says. So, there are a number of individuals that would benefit in knowing the best time of the day to fill-up the gasoline tank.

Typically, gasoline is most dense in the early morning hours when it tends to be coolest outside. Thus, it makes more sense financially to fill-up your car in the morning. Right? Unfortunately, it really does not play out that way.

Gasoline is sold by the gallon in the United States. Therefore, why should it matter when you fill-up your gasoline tank? Gasoline's density changes based on outside temperatures. A colder gallon of gasoline contains more energy than a warm gallon, even though they might cost the same.

The science sounds good, but the actual density change of gasoline is so small that it is impractical to change schedules just to obtain fuel extra early in the morning. Most gasoline stations store their fuel underground in heavily insulated tanks. According to a Consumer Reports study, the small amount of gas that sits above ground may warm up if it sits there long enough. But, if the gasoline is flowing on a busy day, it would not matter. Even if there is a lull between customer fill-ups, those few slightly warmer gallons will not affect the value of a whole tank.

The Consumer Reports study also mentioned that gasoline that rises in temperature from 60 to 75 degrees Fahrenheit only increases in volume by 1 percent [source: Hard].

When gas prices are lower, that will not affect the per-gallon price much, probably just a few cents averaged out over a full fill-up. If someone was driving out of the way to fill-up in the early morning would probably burn up more fuel going off course than they would be likely to save. Even though gasoline should be the most dense in the morning (or whenever air temperatures are the coolest) there are several other factors preventing this from being an effective, cost-saving fill-up strategy.

Regardless, the SQ Group wishes you safe travels this Thanksgiving.