When the weather is hot, your engine will warm up faster, and summer grades of gasoline actually have slightly more energy, creating greater efficiency. Warm air temperatures (or, let’s face it, in the South we are talking about HOT air) also cause less aerodynamic drag, so your car requires less energy to maintain the same speed.
The down side is that using the air conditioning or riding with the windows down, can reduce your vehicle’s energy efficiency. In fact, using the AC under very hot conditions can reduce a car’s fuel efficiency by more than 25%. With hybrid vehicles, plug in hybrids and electric vehicles, the effect is even greater. By the same token, you might think you are saving energy when you drive with the windows down, but it actually increases aerodynamic drag, requiring your car to use more energy.
Here are some tips to help you save fuel when summer temperatures are on the rise.
• 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.
• Park in the shade or use a sunshade so that the cabin doesn’t get as hot.
• 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.
Source: U.S. Department of Energy
Did you know? The EPA says a vehicle can lose up to 2 percent of its miles per gallon for each 100 pounds of additional weight. When you get ready to pack the car for your family vacation, remember that how much you carry with you can affect your fuel costs on the road. The lighter the load the better fuel efficiency you will have.