The Biden administration is set to begin reversing Trump era policies that limited California’s ability to set vehicles’ emissions standards at a more stringent level than required by the federal government.  The Environmental Protection Agency is set to propose a waiver empowering California to mandate zero emission vehicles and to regular greenhouse gas emissions from tailpipes.  Before being blocked by the Trump EPA, California’s requirement set a model for the nation and was expected to be followed by states representing more than one-third of the U.S. auto market.  The transportation sector is now the largest single source of greenhouse gas emissions in the United States, and the Biden administration has promised aggressive action to combat climate change including more stringent auto emissions reduction requirements.