6 Common Reasons for Poor Gas Mileage

6 Common Reasons for Poor Gas Mileage

27th May 2021

close-up of hand pumping gas

Have you been filling up your vehicle at the gas station more frequently than usual? Assuming your driving habits haven't changed, your vehicle may have poor gas mileage. Gas mileage is a measurement of how much gas your vehicle burns per mile driven. While some vehicles are naturally more efficient than others, poor gas mileage is often attributed to the following.

#1) Underinflated Tires

Underinflated tires can lead to poor gas mileage. Research shows that underinflated tires cause a loss of about 0.2% for every pounds per square inch (PSI) of pressure. If your tires are 5 PSI underinflated, your vehicle's gas mileage will drop by about 1%.

#2) Worn Spark Plugs

Your vehicle will burn gas if it has worn or otherwise degraded spark plugs. Spark plugs, of course, are responsible for igniting the mixture of air and gas in the combustion chamber of your vehicle's engine. Like most automotive parts, spark plugs can wear down. If your vehicle has worn spark plugs, it may produce too little or too much spark, which can manifest in the form of poor gas mileage.

#3) Bad O2 Sensor

Another common cause of poor gas mileage is a bad oxygen (O2) sensor. Most vehicles have at least one O2 sensor. O2 sensors are devices that measure the amount of oxygen going into or coming out of the engine. With a bad O2 sensor, your vehicle may fail to correctly read the amount of oxygen going into the engine. To compensate, it may burn additional gas.

#4) Running the AC

While there's nothing wrong with running the (AC) during the summer, it may lead to poorer gas mileage. Automotive AC systems draw power from the alternator. The alternator, in turn, is powered by the engine. Running your vehicle's AC will force the engine to work harder, which may cause poorer gas mileage.

#5) Using the Wrong Engine Oil

Don't make the mistake of using the wrong engine oil. In addition to causing premature wear and tear, it may force your vehicle to burn more fuel. Refer to your vehicle's owner manual to determine which type of oil is best for its engine.

#6) Dirty Engine Air Filter

Neglecting to replace your vehicle's engine air filter can cause poor gas mileage. Engine air filters aren't the same as cabin air filters. Your vehicle's cabin filter is designed to remove pollutants from the air that enters the cabin. The engine filter, on the other hand, is designed to remove pollutants from the air that enters the engine. If the engine air filter is dirty, you may experience poor gas mileage.