Which maintenance task is critical for improving fuel efficiency?

Regular air filter replacement is essential for improving fuel efficiency because the air filter plays a crucial role in the air intake system of an engine. A clean air filter allows for optimum airflow into the engine, which is necessary for efficient combustion. When the air filter is clogged or dirty, it restricts the flow of air, leading to a less efficient combustion process, which can cause the engine to work harder and consume more fuel to maintain the same power output. In contrast, a clean air filter helps the engine run more smoothly and efficiently, leading to better fuel economy.

While regular oil changes, tire rotation, and changing the fuel filter also contribute to overall vehicle performance and maintenance, their direct impact on fuel efficiency is not as significant as that of the air filter. Regular oil changes keep the engine lubricated for smoother operation, tire rotation ensures even tread wear, and changing the fuel filter prevents contaminants from disrupting fuel flow, but the air intake system is heavily reliant on the condition of the air filter for optimal fuel efficiency.