To improve fuel efficiency and facilitate handling of the vehicle in a dense city environment, it should be as small as possible given its intended application. This downsizing trend impacts the size of the engine bay, where the air filter box has to be packed in a reduced space, still without increased pressure drop, reduced load capacity nor lower filtering efficiency. Due to its flexibility and reduced cost, CFD simulations play an important role in the optimization process of the filter design. Even though the air-flow through the filter box changes as the dust load increases, the current modeling framework seldom account for such time dependence. Volvo Car Corporation presents an industrial affordable model to solve the time-dependent dust load on filter elements and calculate the corresponding flow behavior over the life time of the air filter box. The implemented semi-empirical simulation algorithm integrates several sub-models derived from different studies on flows over pleated filters. This work also introduces an experimental method to record the dust pattern on the filter element in order to validate the numerical results. Test results show that the overall dust load as well as its distribution within the filter element can be estimated accurately.