Cal. Health & Safety Code § 43018

(a) The state board shall endeavor to achieve the maximum degree of emission reduction possible from vehicular and other mobile sources in order to accomplish the attainment of the state standards at the earliest practicable date.
(b) Not later than January 1, 1992, the state board shall take whatever actions are necessary, cost-effective, and technologically feasible in order to achieve, not later than December 31, 2000, a reduction in the actual emissions of reactive organic gases of at least 55 percent, a reduction in emissions of oxides of nitrogen of at least 15 percent from motor vehicles. These reductions in emissions shall be calculated with respect to the 1987 baseline year. The state board also shall take action to achieve the maximum feasible reductions in particulates, carbon monoxide, and toxic air contaminants from vehicular sources.
(c) In carrying out this section, the state board shall adopt standards and regulations which will result in the most cost-effective combination of control measures on all classes of motor vehicles and motor vehicle fuel, including, but not limited to, all of the following:
1. (1) Reductions in motor vehicle exhaust and evaporative emissions.
2. (2) Reductions in emissions from in-use emissions from motor vehicles through improvements in emission system durability and performance.
3. (3) Requiring the purchase of low-emission vehicles by state fleet operators.
4. (4) Specification of vehicular fuel composition.
(d) In order to accomplish the purposes of this division, and to ensure timely approval of the district’s plans for attainment of the state air quality standards by the state board, the state board shall adopt the following schedule for workshops and hearings to consider the adoption of the standards and regulations required pursuant to this section:
1. (1) Workshops on the adoption of vehicular fuel specifications for aromatic content, diesel fuel quality, light-duty vehicle exhaust emission standards, and revisions to the standards for new vehicle certification and durability to reflect current driving conditions and useful vehicle life shall be held not later than March 31, 1989. Hearings of the state board to consider adoption of proposed regulations pursuant to this subdivision shall be held not later than November 15, 1989.
2. (2) Notwithstanding Section 43830, workshops on the adoption of regulations governing gasoline Reid vapor pressure, and standards for heavy-duty and medium-duty vehicle emissions, shall be held not later than January 31, 1990. Hearings of the state board to consider adoption of proposed regulations pursuant to this subdivision shall be held not later than November 15, 1990.
3. (3) Workshops on the adoption of regulations governing detergent content, emissions from off-highway vehicles, vehicle fuel composition, emissions from construction equipment and farm equipment, motorcycles, locomotives, utility engines, and to the extent permitted by federal law, marine vessels, shall be held not later than January 31, 1991. Hearings of the state board to consider adoption of proposed regulations pursuant to this subdivision shall be held not later than November 15, 1991.
(e) Prior to adopting standards and regulations pursuant to this section, the state board shall consider the effect of the standards and regulations on the economy of the state, including, but not limited to, motor vehicle fuel efficiency.
(f) The amendment of this section made at the 1989–90 Regular Session of the Legislature does not constitute a change in, but is declaratory of, the existing law.