To reduce the United States’ GHG emissions by at least 80% from 1990 levels by 2050 will require multiple legal pathways for changing its transportation fuel sources. The DDPP reports characterize the transformation required of the transportation system as part of the third pillar of fundamental changes required in the U.S. energy system: “fuel switching of end uses to electricity and other low-carbon supplies.” Relying upon the 2015 DDPP analysis, the chapter addresses that challenge as applied to light-duty vehicles (LDVs) such as cars and sport utility vehicles. Specifically, the DDPP authors anticipate two changes required for our LDV fleet by 2050: (1) increased fuel economy standards in excess of 100 miles per gallon; and (2) deployment of approximately 300 million alternative fuel vehicles, which for purposes of the chapter consists of electric vehicles (EVs), hybrids (electric and gas), and hydrogen vehicles. The goal is to shift 80%-95% of the miles driven from gasoline to lower carbon energy sources like electricity and hydrogen. The chapter identifies key legal pathways to advance these two goals, focusing on actions to both facilitate the growth of alternative fuel vehicles and to limit the production and use of gas and diesel-fueled vehicles.