Performance standards have a long history in the US transportation sector, beginning at the national level with the Corporate Average Fuel Economy (CAFE) standards enacted by Congress in 1975 (Greene 1990), and in California with the Zero Emission Vehicle (ZEV) program adopted by the California Air Resources Board (CARB) in 1990 (Collantes and Sperling 2008). Unlike technology mandates, which prescribe specific technology (e.g., a three-way catalytic converter), performance standards set a goal (e.g., maximum emissions per unit of performance, or vehicle efficiency of at least x miles per gallon), enabling the regulated entity to choose any technology mix that achieves that outcome (Bergek and Berggren 2014). Performance standards can force technology innovation by specifying a standard that cannot be met with conventional technology (Lee et al. 2010) or that imposes higher cost (Gerard and Lave 2005). When implemented as technology volume requirements (e.g., requiring that products with a specific technology constitute x percentage of all new sales), performance standards push an identified technology into the market, usually with the intent of achieving cost reductions through market penetration. When implemented as an emissions intensity standard, performance standards provide flexibility by enabling compliance through incremental improvements without specifying technology choice. Tradability or averaging of performance across facilities introduces additional flexibility and thus improves the cost-effectiveness of the policy.