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What Causes Poor Gas Mileage? (And How to Fix it)

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Higher gas prices can put a pinch on household budgets. Drivers who have to fill up multiple vehicles or are on the roads more often may feel the most pain at the pump.

Buying a more fuel-efficient car is one solution for combating high gas prices, though that's not always realistic. Understanding the various causes for poor gas mileageand taking steps to address them can be an easier way tomake the most of your current vehicle's fuel efficiency.

What Affects a Car's Miles Per Gallon?

On average, vehicles in the U.S. have become substantially more fuel-efficient over the last several decades. According to the Environmental Protection Agency's 2021 Automotive Trends Report, the average fuel economy for all 2020 model vehicles on the road is 25.4 miles per gallon (MPG).

How much gas mileage you're getting can depend on several factors, including:

  • How and where you drive
  • Vehicle condition and maintenance
  • Type of fuel used
  • Vehicle variations, including age, make and model

Many of the main causes for poor gas mileage are mechanical and include things like improper air flow, faulty injectors or bad oxygen sensors.

"Your vehicle needs both fuel and air to give the best fuel mileage," says Nicole Miskelley, manager at PMR Auto & Diesel Repair in Marion, Illinois. When one part of the system malfunctions, that can throw off your fuel usage and hurt gas mileage.

Aside from mechanical issues, other factors can affect gas mileage. Miskelley says bad alignment, improperly inflated tires, poor tread and driving habits can make a difference in how far a gallon of gas goes.

"Poorly maintained tires can cause your car to pull harder and do extra work to get going," says Miskelley. "If the tire is improperly inflated or aligned, you could be battling against gravity to go down the road."

Worn brakes can also be an issue, says Robert Walden, a mechanic with over 15 years of experience and founder of Vehicle Freak.

"Brake pads tend to get sticky as they wear out, and as old brakes apply resistance to the engine, it's forced to work harder," says Walden. "When the engine has to work harder, it burns more fuel, and you'll get fewer miles out of each gallon."

Speeding or making frequent stops and starts can also be culprits of poor gas mileage. The Department of Energy estimates that aggressive driving can lower gas mileage by 15 to 30 percent at highway speeds and 10 to 40 percent in stop-and-go traffic. Meanwhile, idling wastes six billion gallons of fuel each year.

How to Improve Gas Mileage

Some of the causes for poor gas mileagecan be more obvious than others. For example, if your vehicle frequently "pulls" to one side while driving, that could be a clue it's out of alignment. Miskelley says that keeping up with maintenance can help you spot and prevent issues that may drain your vehicle's fuel economy.

Basic vehicle maintenance includes things like:

  • Getting regular oil changes
  • Having the air filter checked regularly
  • Performing tune-ups based on the manufacturer's recommended schedule

It's also important to pay attention when your vehicle is trying to tell you something.

"When the check engine light comes on or you notice your vehicle running differently, having repairs done right away can not only return you to good fuel mileage, but it can keep your car in tip-top shape to last for the long run," says Miskelley.

Aside from basic maintenance, you can also focus on specific areas that tend to be trouble spots. For example, Walden suggests cleaning fuel injectors to avoid clogs that could slow your vehicle down, keeping tires properly inflated throughout the changing seasons and having a mechanic inspect your brakes each time you get an oil change to ensure they're in good working order.

Does changing spark plugs improve gas mileage? It can, if worn spark plugs are misfiring, which can drain fuel efficiency. Likewise, replacing sagging belts and maintaining the appropriate level of transmission fluid can help boost gas mileage.

Safe Driving Can Save on Gas—and Insurance Costs

Changing your driving habits is one more way to get better gas mileage.

Observing speed limits and reducing idling time can also help fuel go farther. For instance, every five miles you drive over 50 miles per hour is the equivalent of paying $0.22 cents more per gallon, according to the Department of Energy.

"Gentle braking and take-off are easier on your fuel and your engine," says Miskelley. "Cruise control can be your best friend to keep you from varying speeds without realizing it."

As mentioned, avoiding aggressive driving can also help to make your vehicle more fuel-efficient. It can also result in savings in a different way if you're able to get lower car insurance rates based on your driving history and activity.

Westfield offers flexible insurance options to cover a variety of vehicles, including cars, trucks, SUVs and motorcycles. Get in touch with your local Westfield agent today to discuss auto insurance options that fit your budget and needs.