Thursday, January 6, 2010

Do you really get more gas in your tank on cold days? Good question.

This theory isn't new and the science behind it makes sense. It was widely believed that if you fill up your tank on cold days, or on cool mornings or evenings, you'll actually get more fuel in your vehicle.

The reason is because gas is more dense when it's cold, so a gallon of cold gas will contain more energy content than a gallon of warm gas.

While this is true, gasoline is stored in underground tanks where the temperature doesn't really change. Also, according to popular mechanics, most vehicles will compensate the mixture no matter what the temperature of the gas is.

Additionally, most modern day fuel pumps are temperature regulated to compensate for differences in density.

Add all this together and you start to realize that it really doesn't matter when you put gas in your car.

Fuel economy itself usually gets worse in winter. Tire air pressure decreases and your engine has to work a little harder because the fluids get thicker, making them more difficult to pump.