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Hot and cold climates don't require different automobile fuels, but governments may promote or require different types of gas for environmental reasons. Because the weather can exacerbate the negate effects of exhaust, different automobile fuels, or perhaps more precisely, different blends of gasoline, can be used to offset the impact gas-powered vehicles have on the environment. In the United States, for example, oxygenated fuels may be used in the winter months and volatility requirements may be imposed in the summer months.
If you have trouble understanding the difference between a summer blend of gas and winter blend you are not alone. The US government, for example, uses such terms as RVP (Reid Vapor Pressure) and PSI (Pounds per Square Inch) to monitor the properties of gasoline. While the chemistry and terminology may be confusing, the overall concept is relatively simple.
In the US, the federal government has volatility requirements which imposes certain gasoline blends in the summer in order to cut down on emissions and smog. This is done by reducing the amount of gasoline that evaporates into the atmosphere by removing some of the chemical properties in the gas. Generally, summer blends are only used from the beginning of June until September, and are specifically targeted at warm climates. Summer blend gasoline may be better for the environment but, especially in colder climates, it can render vehicles nearly inoperable as the combustibility is not as great. This reduced level of combustion can make vehicles harder to start at colder temperatures.
Different automobile fuels are also created for use in the winter. In addition to volatility requirements, for example, the US government has an Oxygenated Fuel Program which focuses on using fuel additives that contain oxygen. The increased amount of oxygen in the gasoline helps the gas burn cleaner and reduces emissions.
As an interesting side note, the federal government only mandates summer blends in 12 metropolitan areas. However, some legislatures have enacted the same mandates statewide. California’s rules are the most strict, beginning its requirement in May, rather than June. As for the Oxygenated Fuel Program, states manage that nationwide.
So why does gas cost more in the summer? It is true that the blends are more expensive to produce, but the expense is minimal, only approximately a penny per gallon. The real price spikes come at the beginning of summer and the end of summer, during the switchover periods. This causes temporary shortages, which leads to temporary price spikes until things settle into equilibrium once again.
For those who claim they do not remember such seasonal price spikes when they were younger, that is probably correct. Seasonal gasoline recipes producing these different automobile fuels have only recently been part of the picture. In the US, the change in blends began in the late 1980s as part of new environmental regulations.