Tailpipe Emission Standards
In 2004, the California Air Resources Board (CARB) adopted a rule requiring automakers to begin in the 2009 model year (MY) to phase in lower-emitting cars and trucks that will collectively emit 22% fewer greenhouse gases than 2002 vehicles in MY 2012 and 30% fewer in MY 2016. A suite of other states opted to sign on to California's more stringent standards. In 2012, CARB adopted new GHG standards for model years 2017 to 2025. Federal standards were subsequently finalized, bringing nationwide standards in line with California standards. However, California has, in addition, and updated zero-emission vehicle program that requires increasing production of plug-in and fuel-cell vehicles from 2018 to 2025. The GHG reductions are expected to be achieved largely, though not entirely, through improved vehicle efficiency, so these standards are in effect energy efficiency policies. Several technologies stand out as providing significant, cost-effective reductions in emissions. Among others, these include the optimization of valve operation, turbocharging, improved multi-speed transmissions, and improved air conditioning systems.