Bad gas mileage in a vehicle may be caused by a number of different things, some common and some not so common. What follows is a brief list of some of the most common causes of bad gas mileage.
Car tires that are improperly inflated create significant road resistance and drag on a moving car. A car engine has to work harder to propel a car forward due to this increased tire/road resistance. This resistance chips away at a car's gas mileage.
A dirty air filter impedes air flow into a car's engine, a process that disrupts normal engine combustion and makes it less efficient. This causes a reduction in both engine performance and gas mileage.
Spark plugs are responsible for igniting a car's air/fuel mixture, an event that causes a mini explosion inside a car's engine cylinders. Bad or dysfunctional spark plugs don't fire, or ignite, properly; thus, they affect engine combustion negatively, which in turn negatively affects gas mileage.
For a car to be at its most fuel efficient, its oxygen sensors, small and electronically operated, automatically adjust a car's air/fuel mixture and have to be functioning properly. Bad oxygen sensors cause abnormal air/fuel mixture ratios, a condition that results in poor gas mileage and poor vehicle performance.
A car's fuel injection system is responsible for injecting precise amounts of fuel into a car's engine cylinders, where it is combined with air and ignited. For a car to perform properly, a specific amount of fuel has to be injected by each fuel injector into each engine cylinder. A leaky fuel injector wastes fuel by leaking it outside the engine and reducing the amount of fuel that makes it into the engine. This results in wasted fuel and reduced gas mileage.
