Presented herein are velocity and particle concentration profiles that were measured in planes just upstream and downstream of an engine air intake filter (AF3192) with a Laser Doppler Velocimeter. These detailed measurements allow the computation of local filter efficiency, with overall efficiency being an integral of the local efficiencies. Measurements were performed for nominal air flow rates ranging from 34 m3/hr to 268 m3/hr with monodisperse polystyrene latex spheres of 0.966, 5.3 and 10.2 micron diameters. Two test housings were employed in the research -- the SAE J726 housing (for engine tests) and a small angle diffuser housing that is similar to the SAE J1669 housing (for cabin filtration tests). The SAE housing generally had a higher filtration efficiency than the small angle diffuser housing, and the SAE housing overall efficiency＇s variation with air flow rate was flatter than that of the diffuser housing. As expected from Stokes number considerations, the large particles had higher filtration efficiencies than the small particles, and the overall filtration efficiencies of 30% to 80% were within the range predicted by theoretical models and gravimetric testing. Work will continue with more particle sizes, SAE dust, various contaminant loading (dirty filters), charged/charge neutralized systems, and housing more representative of actual installed [in the automobile] geometries.