Gas Cheaper With More Butane

Have you seen cheaper gas in rural areas? Certainly you have heard about summer blend gasoline being more expensive. The common factor influencing both is air pollution. In hot temperatures, gasoline evaporates into the air and creates polluting smog. Gasoline is actually a mixture of many components, some of which are cheaper than others. Some also evaporate more easily. It turns out that butane is one of the cheaper components of gasoline, but it also evaporates easily. Thus to reduce evaporation in the summer heat, the gasoline has to have less butane. But that also means less of one of the cheapest components, which raises the price as well as reducing evaporation.

In congested cities, environmental regulations are often stricter, which implies the gasoline must be more resistant to evaporation. So in cities as in summer, the easy to evaporate but cheap butane must be replaced with something with a higher price.