California's Zero-Emission Vehicle Mandate: Linking Clean-Fuel Cars, Carsharing and Station Car Strategies

To reduce transportation emissions and energy consumption, policy makers typically employ one of two approaches—changing technology or changing behavior. These strategies include demand management tools, such as ridesharing and vehicle control technologies that involve cleaner fuels and fuel economy. Despite the benefits of a combined policy approach, these strategies are normally employed separately. Nevertheless, they have been linked occasionally, for instance in the electric station car programs of the 1990s. Station cars are vehicles used by transit riders at the start or end of a trip. In 1990, the California Air Resources Board (CARB) focused on reducing mobile air pollution by mandating that automakers introduce clean vehicles through its Zero-Emission Vehicle (ZEV) Mandate. In 1998, significant flexibility was introduced through partial ZEV credits for very-low-emission vehicles. In 2000, CARB left the ZEV mandate intact, but began considering new approaches, including station cars and carsharing. Carsharing is the short-term use of a shared-use vehicle fleet. In January 2001, recognizing the potential for station cars and carsharing to further improve air quality by reducing vehicle miles traveled—particularly with transit linkages—CARB proposed additional ZEV credits for vehicles in such programs. Thus, the mandate would formally link demand management and clean vehicles. Explored are carsharing and station car developments, lessons learned, the ZEV mandate, and the proposed credit structure. Finally, policy and research recommendations are discussed for enhancing the success and effect of this combined approach.