8 Main Causes of Bad Gas Mileage

November 8, 2016

Bad gas mileage is caused by a number of different things. The list goes on and on, but there are various things that attribute to this problem. Bad gas mileage means that your car is not running as efficiently as it could, and it also means you are losing money at the pumps because you are filling up more often. Here are some of the main causes of poor gas mileage.

See this month's best deals on fuel-efficient cars >>

Bad Gas Mileage Causes:

  • 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.
  • Having bad oxygen sensors and air filters can reduce your gas mileage by up to 20%. The oxygen sensors help keep the proper mixture of air and fuel, and having this off balance can be inefficient. The air filters can get clogged and simply need to be unclogged to fix the problem. Air filters need to be cleaned so that the engine can work at its peak performance.
  • Your spark plugs are responsible for sparking combustion in your engine. If they misfire, or are working poorly, this can affect your gas mileage in a negative way.
  • Having bad fuel injectors can cause bad mileage. This is because the fuel injectors are responsible for putting fuel into the engine. If there is a leak of some sort, then less fuel will make it to the engine, and then in turn make it run less efficiently.
  • Having your air conditioner on causes a lot of gas to be wasted in powering the system. Depending on your local climate, consider turning off the air conditioner when it makes sense and ride with your windows open. At higher speeds, close the windows though to reduce drag.
  • A common cause of bad mileage is your own driving habits. If you are an aggressive driver, likely you accelerate to quickly. This causes more fuel to be used, and will use up more gas than you need. Same goes for revving your engine. It may sound cool, but it uses up gas for going nowhere.
  • Many people waste gas by idling. Idling is when you have your engine on, but you are parked and not moving. Common places where this occurs is when you are trying to warm up your car in the winter, or while you are waiting to pick someone up. Your car really doesn't need more than 30 seconds to warm up the engine. When it comes to waiting for someone, turn your car off or put it into neutral. Since you aren't moving, you might as well save gas and the environment.
  • The type of motor oil that you are using can also affect your gas mileage up to 12%. You want to use motor oils that are high in reducing friction. Either use a synthetic oil or the oil that the car's manual recommends.

Overall, these are the major causes of bad gas mileage, but the list goes on even further than this.

Browse our Buying Guides for top vehicle picks in each segment >>