Troubleshooting Fuel Efficiency: Why Your Car's Mpg Is Dropping

If you're noticing a drop in fuel efficiency and you don't live in the frozen north, and you don't own a lead foot, it's time to take a look under the hood and perhaps your tires. Incorrect tire pressure is a common cause of bad gas mileage and is one of the easiest things to correct. Tires that are underinflated mean more friction, traction and resistance. The more resistance, the more gas it takes to keep your tires rolling. Driving habits can also lower your mileage.

Driving habits

• Avoid sudden acceleration: Sudden acceleration when the light turns green can significantly impact your car's fuel efficiency. Try to accelerate smoothly and gradually to improve your fuel economy.
• Maintain a steady speed: Driving at a steady speed can help you conserve fuel. Avoid frequent changes in speed, as this can waste fuel.
• Use cruise control: Using cruise control on highways or open roads can help you maintain a steady speed and improve your fuel efficiency.
• Avoid high-speed driving: Driving at high speeds can significantly impact your car's fuel efficiency. Try to maintain a moderate speed to improve your fuel economy.
• Avoid aggressive driving: Aggressive driving can also impact your car's fuel efficiency. Try to drive defensively and avoid sudden stops and starts.
• Maintain a steady pace: Maintaining a steady pace while driving can help you conserve fuel. Avoid frequent changes in pace, as this can waste fuel.
• Use the right gear: Using the right gear while driving can also help you improve your fuel efficiency. Try to avoid using high gears at low speeds.
• Avoid idling: Idling can waste a significant amount of fuel. Try to avoid idling for extended periods, especially in traffic jams or while waiting for someone.
• Maintain your car: Regular maintenance of your car can help you improve your fuel efficiency. Ensure that your car's engine, tires, and other components are in good working condition.

By following these tips, you can improve your driving habits and potentially increase your car's fuel efficiency.

Incorrect tire pressure

Periodically checking your tires with an inexpensive pressure gauge is a good way to catch this. Just be sure to use your car manufacturer's recommended pressure levels stamped onto the driver's side doorplate and not the "maximum pressure" numbers shown on the tire itself.

Driving with incorrect tire pressure is also bad for your tire tread and alignment.

Turn off the air conditioner when you don’t need it as it will drastically affect your mileage.

Check your driving habits and see if you have become a more aggressive driver or if you have been revving your engine more than normal.

Faulty oxygen sensor

A faulty oxygen sensor can cause your car to lose fuel efficiency. Oxygen sensors are responsible for the air-to-fuel ratio of your engine and typically last the life of the car. When they are faulty, they send false, lean-bias alarms and deem the engine to be lean or low on fuel, adding unnecessary additional fuel to the system. This unneeded fuel just goes to waste and drastically affects your mileage.

Cold temperatures can also cause a decrease in fuel efficiency. A faulty or inaccurate coolant sensor means your car may think it’s cold when it’s actually warm out, and the extra fuel your car sends into the engine gets wasted.

If you are noticing drops in gas mileage and you don’t live in the frozen North, and you don’t own a lead foot, it’s time to take a look under the hood and perhaps your tires. Incorrect tire pressure is a common cause of bad gas mileage and is one of the easiest things to correct. Tires that are underinflated mean more friction, traction and resistance. The more resistance, the more gas it takes to keep your tires rolling.

Other causes of poor gas mileage include incorrect tire pressure and/or poor alignment, use of air conditioner when not necessary, and stuck brake caliper. Driving habits can also lower your mileage, such as turning into a revving machine, being a more aggressive driver, or warming your car up more than normal.

Cold temperatures

Driving habits can also cause a drop in fuel efficiency when it is cold. Warming up the car more than normal can be a habit that lowers mileage.

Incorrect tire pressure is a common cause of bad gas mileage and can be corrected by periodically checking your tires with an inexpensive pressure gauge. Tires that are underinflated mean more friction, traction and resistance, which requires more gas to keep your tires rolling.

Using the air conditioner when not necessary can also drastically affect your mileage, so remember to turn it off when you don’t need it.

A stuck brake caliper can also be an indicator of a drop in fuel efficiency. If your vehicle is pulling to a side, this could be a sign that the brake caliper is stuck.

Age of the car

As a car gets older, its fuel economy declines. No matter how well you take care of your vehicle, its engine efficiency and power are never as good as when you drive it off the lot. This decrease in efficiency is most likely due to faulty or worn engine components.

Incorrect tire pressure is a common cause of bad gas mileage. It's also one of the easiest things to correct. Periodically checking your tires with an inexpensive pressure gauge is a good way to catch this. Just be sure to use your car manufacturer's recommended pressure levels stamped onto the driver's side doorplate and not the "maximum pressure" numbers shown on the tire itself.

Tires that are underinflated mean more friction, traction and resistance. The more resistance, the more gas it takes to keep your tires rolling.

A stuck brake caliper is like tugging on your own cape if your vehicle is pulling to a side, this could be an indicator.

Driving habits can also lower your mileage. Have you turned into a revving machine, a more aggressive driver, or has the cold weather got you warming your car up more than normal? These are all habits that can lower your mileage.

Frequently asked questions