California Code, Health and Safety Code - HSC § 43102

(a) No new motor vehicle or new motor vehicle engine shall be certified by the state board, unless the vehicle or engine, as the case may be, meets the emission standards adopted by the state board pursuant to Section 43101 under test procedures adopted by the state board pursuant to Section 43104.

(b) Notwithstanding subdivision (a), to assure that California consumers have an adequate selection of light-duty motor vehicle models, the state board shall adopt certification and enforcement regulations for future model years as soon as practicable, but not later than for the 1983 and subsequent model years, which will allow a manufacturer to certify in California federally certified light-duty motor vehicles with any engine family or families when their emissions are offset by the manufacturer's California certified motor vehicles whose emissions are below the applicable California standards. This exemption shall not apply to emergency vehicles, as defined in Section 2002 of Title 15 of the United States Code.

(c) Subdivision (b) shall not be applicable to any vehicle or engine model which is certified to meet the emission standards established pursuant to Section 43101 or 43101.5.