In order to be effective in car ventilation applications, an air filter must possess suitable capabilities in each of the following categories: efficiency, pressure drop, dust holding capacity, strength, temperature, humidity and chemical resistance. An evaluation method should provide clear information on the filter characteristics in each of these areas. The most important are pressure drop, dust holding capacity, and gravimetric and fractional efficiencies. They depend on the filter media, air flow, air contaminants and environmental conditions.This paper discusses automotive filter environments in order to understand problems experienced in the field. The influence of several factors involved in car interior air filter performance are evaluated.