Air filtration is a well-known approach to improve the automotive indoor air quality. The objective of the study reported here has been to develop an in-situ measurement protocol to assess the efficiency of particulate filtration systems. A large set of actions (air flow modeling, particle sampling and transport efficiency, etc.) has been carried out to define a sampling line to measure the upstream particle concentration. PM10, PM2,5 et PM1 mass concentration have been measured by gravimetry. Two field campaigns have been carried out with an equipped car moving in the Paris area, to test the protocol on two different cabin filters.