Gas prices swing up and down unpredictably, but there's one thing in your control: how efficiently your car uses what's in the tank.

The gap between a well-driven, well-maintained vehicle and a neglected one with bad habits behind the wheel can be dramatic — we're talking 10 to 40 percent in fuel economy depending on driving conditions.

<h3>Smooth Acceleration Makes a Big Difference</h3>

Stomping on the gas pedal from a stop is one of the fastest ways to drain a tank.

According to the U.S. Department of Energy, aggressive acceleration reduces gas mileage by 15 to 30 percent on the highway and 10 to 40 percent in stop-and-go traffic. The fix is simple: press the accelerator gently and build speed gradually. Think of it as easing into momentum rather than demanding it all at once. The engine works less, the transmission shifts more smoothly, and fuel consumption drops.

<h3>Speed Is the Other Big Factor</h3>

Gas mileage typically starts dropping quickly above 50 mph. Each 5 mph over that costs more fuel per mile — the aerodynamic drag increases exponentially. On the highway, using cruise control keeps your speed steady and prevents the small speed fluctuations that waste fuel. If you're able to slow down 5 to 10 mph on highway stretches, the fuel savings over a year of regular driving add up noticeably.

<h3>Tire Pressure — Seriously, Check It</h3>

Under-inflated tires increase rolling resistance, which means the engine has to work harder to move the car at the same speed. Keeping tires properly inflated can improve gas mileage by 0.6 percent on average and up to 3 percent in some cases. Check the sticker on the inside of the driver's door for the correct PSI — not the number printed on the tire's sidewall — and check monthly.

<h3>Lighten the Load</h3>

Extra weight reduces efficiency. That roof cargo box sitting on top of your car even when empty creates aerodynamic drag. A large rooftop box can reduce highway fuel economy by 10 to 25 percent at interstate speeds. Remove it when it's not needed. Clear out the trunk of anything that doesn't need to be there. Each extra 100 pounds reduces fuel efficiency by roughly 1 percent.

<h3>Maintenance Matters More Than People Think</h3>

Worn spark plugs reduce combustion efficiency and can drop gas mileage by up to 30 percent. A dirty air filter restricts airflow to the engine, forcing it to work harder. A faulty oxygen sensor can disrupt the fuel mixture and increase consumption by up to 40 percent. Regular maintenance keeps these components in working order — which means a well-maintained car naturally uses less fuel than a neglected one doing the same miles.

<h3>Use the Right Fuel</h3>

Unless your owner's manual specifies premium fuel as required, using regular 87-octane is perfectly fine. Using premium when it isn't needed adds cost without any meaningful performance or efficiency benefit. The manual's recommendation exists for a reason — follow it in both directions.