With gas prices skyrocketing and the temperature not far behind (at least here in New England) there is always talk about how to save money on gas. One topic which seems to have solidly hit the mainstream lately is the notion that you can save money by buying your gas when it’s cold. This has herds of people buying their gas on cold days or in the wee hours, but is it worth it? Well, consider the following:

Gasoline, like most things, does expand when it’s warm. According to this study performed by a House committee last year the ratio is around 0.069% per degree Fahrenheit. That means if you are paying $3.75 per gallon you may be paying a full 7.7625 cents more per gallon for gas at 90 degree than you would at 60 degrees. That adds up to about 93 cents on a 12 gallon fill up if the gas is a full 30 degrees warmer.

Now, before you run off in the middle of the night to save your scant dollar on a fill up, consider this: Gas is stored in very large tanks, and often under ground. Next time you’re filling up on a warm day feel the temperature of the hose or the metal parts of the nozzle… You’ll probably find that they’re much cooler than the ambient temperature, so the swing in the temperature of gas will vary much less than the temperature of the air.

So for my money, instead of getting up early and wasting gas with a special trip to the station, consider combining some errands, carpooling, or slowing down a couple MPH on the highway. These changes will not only save you money, but also save gas and reduce emissions.