10 Tips to Get the Most Out of a Tank of Gas

When you drive, follow the speed limit and drive smoothly. Your driving habits can play a significant role in fuel economy.

We measured gas mileage while driving at a steady 55, 65, and 75 mph in a Nissan Altima and Toyota RAV4. We found that reducing the speed from 65 mph to 55 mph improved fuel economy by 6 mpg in the Altima and 8 mpg in the RAV4. The penalty for cruising at 75 mph rather than 65 mph was almost 7 mpg in the Altima and 6 mpg in the RAV4. Higher speeds exact a toll on fuel consumption. Another way to look at it: Speeding up from 55 to 75 mph is like moving from a compact car to a large SUV. Beyond fuel concerns, speeding is, of course, a safety risk.

Avoid hard acceleration and braking whenever possible. In our tests, frequent bursts of acceleration and braking reduced an older Toyota Camry’s mileage by 2 to 3 mpg. Once up to speed, maintain a steady pace. The harder you accelerate, the more fuel you use. Unnecessary braking wastes the fuel you used to get up to speed. Drive smoothly and anticipate the movement of traffic. Smooth acceleration, cornering, and braking also extend the life of the engine, transmission, brakes, and tires.

Save money and pass on premium gas unless it’s “required.” This is indicated on the fuel filler door. Many cars list “recommended,” which means it’s optional. If there’s only midgrade or premium fuel available, it will work fine in a car that’s rated for regular gasoline. Our tests show that paying extra for a higher octane means no significant performance or fuel-economy benefits for many cars. (Learn more about why you might not need premium gas.)

Remove roof racks when they’re not being used. At highway speeds, more than 50 percent of engine power goes to overcoming aerodynamic drag.

Using air conditioning consumes gas. In mild weather, if you can get by without it—especially with open windows—you’ll see incremental savings. But once it gets hot, having AC on to cool the cabin and lower humidity is a wise investment in your comfort and ability to stay alert while driving. Our tests show the trade-off can be 1 to 4 mpg, depending on the car, for using AC. We did not see a measurable impact from opening windows at 65 mph.

Apps and websites such as GasBuddy can show local gas prices, making it easy to find good prices in your area or when you travel. Generally speaking, gas stations well off major highways and away from city centers tend to have better prices, as do warehouse stores and some major travel centers. 

If you can delay errands or other activities, you’ll preserve the gas that you purchased and reduce overall consumption for the region, helping in some small way to reduce gas scarcity. 

We typically recommend using Top Tier gas—that is, gas that’s held to a higher standard through the voluntary participation of numerous gas station brands, including Chevron, Costco, Exxon, Mobil, and Shell. Beware that many familiar brands don’t have Top Tier gas. The goal is to feed your car good-quality gas whenever possible, but it’s fair to be flexible during a shortage or when traveling. If you use non-Top Tier gas on occasion, it may cause engine deposits. But the detergents in Top Tier gas can eventually clean any engine deposits that may accumulate. 

Keep at least a half-tank of fuel during cold winter months and when there’s a risk of shortages, say, due to a lack of gasoline delivery drivers to meet travel demands or when a major storm or hurricane is imminent. This tip also applies to holiday road trips, when traffic can be congested and slow-moving. Having plenty of gas onboard can ease stress and give you more flexibility with when and where you fill up.

Monitoring tire pressure is important. Tires lose about 1 psi a month. Having tires with lower pressure than what’s recommended on your doorjamb sticker can affect performance, tire longevity, and fuel economy. 

You may have heard that it’s better to buy gasoline first thing in the morning rather than in the heat of the day. That’s because mornings tend to be cooler, and like all liquids, gasoline expands when heated. It sounds logical—but is it true or just an urban legend?

We conducted our own tests and interviewed experts, and found that although the basic facts are correct, the advice is not. 

Filling stations typically store their gasoline in underground tanks, where the temperature variation during the day is much less than in the air above. The result is that the temperature of the gasoline coming out of the fuel nozzle varies very little, if at all, during any 24-hour stretch at any particular gas station.

The Energy Marketers of America, a trade group that represents filling stations, says that “gasoline pumps dispense a full gallon irrespective of the temperature at the time."

Over a series of tests at different temperatures conducted at our Auto Test Center, we found that even with the temperature swings we observed in the first few gallons pumped at our facility, there wasn’t a significant penalty for consumers. A 15-degree difference, for example, would result in a 1 percent gain in volume. That’s just a few cents’ difference in the first gallons pumped—not enough to change your schedule or routine in chasing costs, especially if it might increase your fuel consumption in the pursuit.