40 CFR § 85.1503 - General requirements for importation of nonconforming vehicles and engines.
(a) A nonconforming vehicle or engine offered for importation into the United States must be imported by an ICI who is a current holder of a valid certificate of conformity unless an exemption or exclusion is granted by the Administrator under § 85.1511 of this subpart or the vehicle is eligible for entry under § 85.1512.
(b) Final admission shall not be granted unless:
(3) The vehicle or engine is exempted or excluded under § 85.1511; or
(c) In any one certificate year (e.g., the current model year), an ICI may finally admit no more than the following numbers of nonconforming vehicles or engines into the United States under the provisions of § 85.1505 and § 85.1509, except as allowed by paragraph (e) of this section:
(1) 5 heavy-duty engines.
(2) A total of 50 light-duty vehicles, light-duty trucks, and medium-duty passenger vehicles.
(3) 50 highway motorcycles.
(e) An ICI may exceed the limits outlined paragraphs (c) and (d) of this section, provided that any vehicles/engines in excess of the limits meet the emission standards and other requirements outlined in the provisions of § 85.1515 for the model year in which the motor vehicle/engine is modified (instead of the emission standards and other requirements applicable for the OP year of the vehicle/engine).