An air filter comprises a rigid, hollow body that may be spherical, cylindrical, rectangular or shaped to conform to available, typically underhood, space. If spherical, it may be assembled from a first, lower hemisphere and a second, upper hemisphere which are secured together about their edges, by, for example a press or interference fit, an O-ring received within complementary, edge adjacent channels, an adhesive or autogenous bonding. Other shapes and configurations may be assembled from a body with, for example, a solid bottom and attachable lid, top or cover. The hollow body is filled with activated carbon filter media or passive fibrous filter media. The upper hemisphere, lid or cover includes an outlet and cap which reduces the possibility of ingesting water into the filter. The lower hemisphere or body includes an inlet fitting to which a hose leading to an outlet or vent in the powertrain component is attached.