Automotive Research

Saving fuel when you drive


You might think you need to buy a new, fuel-efficient car to save gas and lower your emissions. In fact, you can take significant steps every day to drive more efficiently, regardless of the vehicle you own.

The truth of this statement has been proven by fuel-economy research carried out by the Auto Club of Southern California’s Automotive Research Center (ARC). It calculated the mileage motorists normally achieved with their typical driving habits, or sometimes when they drove more aggressively. The ARC compared those results to the mileage motorists obtained when they used the driving, maintenance, and lifestyle techniques described below. The results? In all cases, gas mileage improved—from as little as 25% to as much as 100% (from 10 mpg to 20 mpg).

Drive smart

Easy does it. Accelerate slowly and smoothly instead of racing away from a stop sign or traffic light. Accelerating uses more fuel than any other type of driving, wastes gas, and increases pollution. Just 1 second of high-powered driving can produce nearly the same volume of carbon monoxide emissions as a half hour of normal driving, according to the American Council for an Energy-Efficient Economy.

No need for a warm-up. Unless you’re driving a pre-1980 car, you don’t need to let it warm up before you start driving. That just wastes gas. Follow the starting instructions in your owner’s manual. Most likely, it will tell you to start the car, put it in gear, and drive off at a moderate speed until the engine warms up.

Drive sensibly. Generally speaking, the faster you go, the more fuel you burn, because aerodynamic drag increases exponentially with speed. Drive at a steady speed as much as possible; aggressive driving also can lower your mpg by up to a third, according to the EPA. For example, a car that gets 30 mpg at 55 mph will get only 25 mpg at 70 mph and 22 mpg at 80 mph. Consider moving to one of the slower freeway lanes—doing so is also less stressful. You won’t lose much time by slowing down, either. A 60-mile trip driven at an average speed of 50 mph will take only 12 minutes longer than the same trip driven at an average speed of 60 mph.

RELATED: Find out how driving speed impacts fuel economy.

Anticipate slower traffic and traffic lights. When you see stopped or slowed traffic or a red light ahead, take your foot off the accelerator and coast. Zooming up to the light and then slamming on the brakes wastes fuel and is hard on your car’s suspension and brakes. Cars use very little fuel when coasting, and if you’re driving a hybrid, battery-electric vehicle, or fuel-cell electric vehicle with regenerative brakes, coasting typically will recharge the battery, further improving your mileage. Leaving plenty of space between you and the car in front of you allows you to drive in a relaxed manner and is safer, too.

Put it in “Eco.” Many newer cars (for example, the Hyundai Sonata and even the Corvette Stingray) have an “Eco” mode, which enables you to save fuel when you drive. Pressing the Eco button basically does 2 things: It changes the shift points so the transmission shifts earlier, keeping engine revs down; and it changes the way the throttle pedal responds, so you have to press it down farther to get the same response you would if you weren’t in Eco mode. These 2 features increase fuel economy at the expense of performance. Many hybrids also have an EV mode, which enables drivers to use only electricity for power, though usually only for a few miles at low speeds. The electric-only range for plug-in hybrids is greater, usually 15–50 miles.

Keep it charged. If you drive a plug-in hybrid, you’ll use more electricity and less gas if you keep the battery fully charged. With lithium-ion batteries, “topping off” a partially charged battery doesn’t degrade it or decrease its useful life. However, some manufacturers advise against repeated recharging if the battery is at 95% or higher. Check your owner’s manual or talk to the service personnel at your dealership.

Avoid rush-hour traffic whenever possible. Stop-and-go driving burns more gas, increases pollution, and is generally more stressful than driving during off-peak hours.

Steady as she goes. Studies have shown that driving at a steady speed is much more fuel-efficient than continuously varying your speed. When you drive on the highway (especially on level pavement), use cruise control when it’s safe to do so.

Avoid needless idling. When you get out of your car, turn it off rather than leaving it idling. Letting your car idle for more than a minute uses more gas than turning it off and starting it again, according to the Union of Concerned Scientists. Park and walk into a fast-food restaurant or bank instead of using the drive-through.

Use your air conditioner wisely. Driving with the windows open increases aerodynamic drag, which increases the faster you drive. Air conditioning use in newer cars can reduce gas mileage by about 5% (even more on older cars). To cool off on warm days, open your windows when you’re driving under 45 mph; close them and turn on the air conditioner at higher speeds.

Maintain your vehicle

Stay on schedule. Maintain your vehicle according to the manufacturer’s service schedule, which you can find in your owner’s manual or at the automaker’s website. Regular oil and filter changes, inspection of the emission-control system, and other services will keep your vehicle running smoothly, prolong its life, and save fuel. Learn more about AAA Approved Auto Repair facilities. Each shop is inspected on a regular basis to verify that it meets strict AAA quality standards.

Pump it up. Keep your tires properly inflated, which reduces rolling resistance. For every 3 pounds below recommended pressure, fuel economy goes down by about 1%. The correct inflation information is on the driver’s doorjamb, inside the glove-box lid, or in your owner’s manual. Tires normally lose 1–2 pounds of pressure a month, so buy a good tire gauge and check the air pressure regularly.

Get the junk out of your trunk. Reducing extra weight in your car can save up to 2% in fuel economy for every 100 pounds you remove. Take items such as golf clubs or other sporting equipment, tools, clothing, coolers, etc., out of your car’s trunk when you’re not using them.

Ditch the rack. Carry bulky items in the trunk whenever possible instead of on a roof rack. If you do use a roof rack, take it off when you’re not using it. Roof racks increase aerodynamic drag and can reduce fuel economy even when not being used.

Roll easy. When it’s time to buy new tires, ask about low-rolling-resistance tires. They have stiffer sidewalls, so they save energy by flexing less. A University of Michigan study showed that using low-rolling-resistance tires could save 1–2 mpg, or about 32 gallons of fuel a year, based on about 11,000 miles of driving. That equates to about $72 in annual savings, with gas priced at $2.25 a gallon. Check with your mechanic or dealer to find the proper ones for your car.

Don’t upgrade needlessly. Check your owner’s manual to see what grade of fuel your car needs. Most cars are designed to run on regular unleaded; using anything else is a waste of money. If your owner’s manual says “premium required,” use premium. But if it says midgrade or premium is recommended, read carefully; sometimes you can use regular unleaded, although you may experience reduced power or slightly reduced fuel economy. AAA’s study of gasoline use determined that although 70% of cars on the road require only regular gas, 16.5 million U.S. drivers who didn’t need to do so filled their tanks with premium fuel at least once a month, wasting $2.1 billion annually. 

Fill up with care. Gasoline is a hazardous substance. It’s extremely flammable; its fumes are toxic and carcinogenic; it can pollute water and poison wildlife; and spilled gasoline contributes to smog formation when it evaporates. So when you stop to buy gas, don’t top off your tank after the automatic nozzle clicks off.

Keep a log. Track your fuel economy; many new cars display current mpg on their instrument panel, or download an app (type in “fuel economy calculator” to the search function). If your mpg drops suddenly, find out why and fix the problem.

Lifestyle choices

Choose your most efficient vehicle. If you own more than 1 vehicle (nearly 60% of American households do), use the one best suited for the trip you’re taking. According to the EPA, we could collectively save $25 billion in fuel costs and reduce CO2 emissions by 100 million metric tons (equivalent to taking almost 20 million cars off the road) by taking this simple step. So don’t automatically jump into your big SUV if the more fuel-efficient sedan will do.

Check out a rental. Consider renting a fuel-efficient car for vacations and long trips, putting the wear on a rental car instead of your daily driver. Similarly, consider renting a pickup truck instead of buying one if you need a truck to haul things only occasionally.

Plan your route efficiently and combine trips. Doing this will save gas, time, and wear and tear on your vehicle. Use your navigation system or the map on your phone to plan the most efficient route.

Review your commute schedule. Can you change your working hours so you don’t waste time sitting in bumper-to-bumper traffic? Can you carpool or vanpool once or twice a week? How about telecommuting? And before you start your drive, check the traffic app on your smartphone to determine the quickest route. All 4 measures save fuel and reduce vehicle wear.

Drive less. Ask yourself whether you really need to make the trip at all. Consider alternatives such as walking, cycling, or taking public transit.

Just say “no.” Make high fuel economy a priority the next time you buy a car, and pass on those vehicles that get poor gas mileage.

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