Every internal combustion engine needs supply of air. This air is required to be dirt free, dry, clean and cool. Unfiltered air can speedily wear out an engine. In a short period of time the engine can drop compression and power, and begin to emit heavy smoke. As the air filter builds a dust film, the holes in the filter medium become smaller, and the filter becomes more efficient at trapping dirt. As the filter traps dirt, it is difficult for the air to pass through the filter, and restriction increase in the air intake system. Restriction of Air through filter usually remains low, for most of the filter's life service, but increases rapidly at the end. The value of air filter restriction is the key parameter to be used considering filter replacement. The present work is focused on the engine filter technologies and their effect on its performance, emissions and fuel economy.