It seems un-American that gas prices go up just as working families get a few days to drive their cars to have some fun. But it’s not a conspiracy. There are reasons why gas prices increase in the spring and summer. Demand increases because of vacations and that stretches the supply. When natural disasters occur the price increases because transportation is disrupted or refineries are damaged. One consistent reason is that energy companies conduct maintenance on their refineries in the spring, shutting them down and limiting their capacity until late May. This shutdown allows them to change the fuel supply.
This change in the fuel supply, which happens twice a year in the U.S., is known as the seasonal gasoline transition and this is the biggest reason for the increase in price during summer months. Gas sold during the summer is different and more expensive to produce because of the ingredients it contains and because the refineries close.
The seasonal fuel change was initiated in 1995 as part of the Reformulated Gasoline Program (RFG), which was established through the 1990 Clean Air Act Amendments. The Environmental Protection Agency (EPA) created the program to reduce pollution and smog during the summer ozone season, which occurs from June 1 to Sept. 15. Summer-grade fuel burns cleaner than winter-grade fuel, causing it to produce less smog and releases less toxic air pollutants.
The estimates of the actual difference in cost of production is hard to pin down. Estimates exist of an increase of only one cent to two cents per gallon. Other estimates range from three cents to 15 cents per gallon.
The good news is that hot weather can actually increase your fuel economy. A vehicle’s engine warms up to an efficient temperature faster; summer grades of gasoline can have slightly more energy; and warm air causes less aerodynamic drag than cold air.
However, keeping passengers comfortable in hot weather by rolling down the windows or using the air conditioning (AC) can reduce fuel economy.
The guilty party, of course, is the car’s air conditioner. An air conditioner reduces fuel economy in hot weather. Under very hot conditions, AC use can reduce a conventional vehicle's fuel economy by more than 25%. The AC's effect on hybrids, plug-in hybrids, and electric vehicles (EVs) can be even larger on a percentage basis. How much less efficient depends on the outside temperature, humidity and intensity of the sun. Open windows can increase aerodynamic drag. At highway speeds your vehicle needs more energy to push through the air. But you can’t suffocate. Here’s advice for improving fuel economy in hot weather:
• Roll the windows down at lower speeds; use the AC at highway speeds.
• Don't use the AC more than needed or set the temperature lower than needed.
• Drive with the windows open for a short time before using the AC. Letting hot air out of the cabin first will put less demand on the AC and help your vehicle cool faster.
• Don't idle with the AC running before driving. Turn the AC on after you begin to drive or after airing out the cabin briefly. Most AC systems will cool the vehicle faster while driving.
• Read your owner's manual. Most manuals explain how the AC system controls work and how to best use and maintain the AC system.
• For plug-in hybrids and electric vehicles, pre-cooling the cabin while plugged into the charger can extend your vehicle's range. Also, using a warmer temperature setting for the AC will use less battery power.
• Park in the shade or use a sunshade so that the cabin doesn't get as hot.
While these tips may seem obvious, most consumers crank their air conditioner and often do the exact opposite of what is recommended. If you’re looking to save a few pennies, a few conscious changes in the way you cool down may be the answer. Happy summer!