An inlet particle separator system for a vehicle engine includes a hub section, a shroud section, and a splitter. The hub section has a hub outer surface that diverges, relative to the axis of symmetry, to a hub apex. The shroud section has a shroud inner surface that surrounds, and is spaced apart from, at least a portion of the hub section to define a main flow passageway between the hub outer surface and the shroud inner surface. The splitter is disposed downstream of the air inlet and extends into the main flow passageway to divide the main flow passageway into a scavenge flow path and an engine flow path. The hub section and the shroud section are configured such that the cross sectional flow area of the main flow passageway decreases downstream of the air inlet to define a throat section that is disposed upstream of the hub apex.