Many possible factors can lead to poor gas mileage, including driving faster and more aggressively, which both cause the engine to require more fuel to perform less work. In addition to driving habits, using certairn vehicle accessories and features, such as air conditioning, worsens gas mileage by putting additional strain on the engine.
Aside from driving habits, there are a few mechanical problems that affect gas mileage. Bad oxygen sensors and clogged air filters are the most common mechanical causes of bad gas mileage. A clogged air filter reduces the flow of fresh air to the engine, which causes the engine to work harder. The oxygen sensor is responsible for regulating the air and fuel. If it is malfunctioning, it can have a similar effect on the engine.
A malfunctioning fuel injector can also have a significant effect on gas mileage. The fuel injector is responsible for distributing oil, so a leak or malfunction can significantly impact gas mileage. This problem can also cause the engine to perform poorly, which also affects gas mileage. Misfiring spark plugs also contribute to decreasing gas efficiency. Like many other parts, spark plugs that are not working correctly negatively affect the performance of the engine.