How to get better gas mileage in the heat
With gas prices rising to record levels, many drivers are looking for ways to save on fuel.
Whether it’s regular commuting, errands, or a summer road trip, there are ways to get the most out of your gas. When temperatures rise, a vehicle's engine warms up to an efficient temperature faster and summer-grade gasoline can have slightly more energy than it does in the winter. This helps increase how far your car can go on one tank of gas.
Here are some tips:
Be strategic about air conditioning
Let’s be blunt: Running your car's air conditioning contributes to reduced fuel economy in hot weather. Its effect depends on several factors, such as the outside temperature, humidity, and intensity of the sun. Under sweltering conditions, AC use can reduce a conventional vehicle's fuel economy by more than 20 per cent, according to Canada’s Ministry of Energy (MOE). Other government sources put the figure even higher. According to a study by the U.S. Environmental Protection Agency, running your car’s AC when it’s extremely hot can reduce fuel economy by 25 per cent.
The AC's effect on hybrids, plug-in hybrids, and electric vehicles (EVs) can be even larger on a percentage basis.
“Your air conditioner is a really big drain on your gas tank, especially if you're choosing the automatic max function in your car,” Teresa DiFelice, an assistant vice-president at the Canadian Automobile Association's south-central Ontario branch, told CBC recently.
Canada’s MOE recommends trying these tips:
- To regulate the temperature in your car while increasing fuel economy, roll down your windows at lower speeds and switch to using your AC at highway speeds.
- Drive with the windows open for a short time before turning on the AC to allow hot air out of your vehicle. This will help your car cool faster. However, driving with your windows down at high speeds can also increase wind resistance against your vehicle, forcing it to use more energy.
- Consider whether you need AC for cooling. Just as you would at home, adjust your thermostat settings. Aim for comfortable, not cold.
- Use the flow-through ventilation on the highway and open your windows and sunroof while driving in the city.
- Use the “re-circulating” function of your AC system. This uses less energy because you’re cooling only the air already in your vehicle, not bringing in warmer outside air to be cooled.
- Your vehicle will need less cooling from AC at start-up if it’s parked in the shade. If you can’t find a shaded area, use window shades to reduce the heat when it’s parked. Also, don’t use AC when you first start your vehicle. Instead, open the windows for the first few minutes and allow the hot air to escape.
Maintain your vehicle
Keeping your tires properly inflated is a simple way to improve summer gas mileage, say experts at Firestone Complete Auto Care, and it should be reviewed regularly.
You can improve your gas mileage by up to 3 per cent by keeping your tires inflated to the correct pressure, according to the U.S. Department of Energy (DOE). The lower the pressure, the bigger hit to your gas mileage. For every 1 psi drop— pounds per square inch—your under-inflated tires can lower gas mileage by about 0.2 per cent. You can find the recommended psi on a sticker on the driver’s side door jamb or glove box.
Other maintenance helps too. Ensure engine filters are clean, brake fluids are topped up, and do regular oil changes.
Drive safely … and slower
Accelerate slowly and avoid jack rabbit starts. Aggressive driving and hard braking can negatively affect your highway gas mileage. The Canadian Automobile Association (CAA) says to maximize your fuel efficiency, take five seconds to accelerate your vehicle up to 20 km/h from a stop.
By looking ahead at how traffic is behaving, you can often see well in advance when it’s time to slow down, CAA advises. You can also conserve fuel and save money by taking your foot off the accelerator and coasting instead of using the brakes.
Other tips include:
- Slow down on the highway. When it’s safe to do so, use cruise control on long drives. The system keeps speed constant and saves fuel.
- Remove unused roof racks, tail hitch racks, and rooftop boxes to reduce drag. Don’t carry unnecessary items in the trunk.
Don’t idle
You waste one litre of gas every 20 minutes you idle, according to CAA. If you are going to be stopped for 60 seconds or more, try to turn off the engine. Whenever you’re parked for more than 10 seconds, turn off the engine. Don't idle your vehicle with the AC on before starting to drive. Most AC systems will cool the vehicle faster while driving.
Plan your trips
Saving on gas and getting better mileage starts before you get in the vehicle. Plan your errands in a circuit. Pay attention to traffic newscasts to avoid accident zones and other slow-moving areas.
Keep tabs on gas prices
Several websites or apps such as GasBuddy map out gas stations near you and their prices to help you save. News sites will often alert readers when prices are due to rise or drop by a few cents. Many gas stations, credit cards, and other loyalty programs offer discounts on gas. Take advantage of these tools.
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