The U.S. Environmental Protection Agency (EPA) has published proposed rules that would reduce sulfur in gasoline from 30 to 10 parts per million starting in 2017 and phase in other vehicle emission requirements in later years. 78 Fed. Reg. 29,815 (5/21/13). The so-called Tier 3 standards are intended to bring federal requirements in line with California’s stringent vehicle emission restrictions. While the published notice requests comments by June 13, 2013, EPA has extended the comment period to July 1.