The document discusses key drivers of technological change in transportation including air quality, global warming, energy security, and congestion relief. It notes that transportation is the largest single source of greenhouse gas emissions, with passenger vehicles accounting for 27% in 2006. To reduce emissions, more non-carbon based fuels like electricity and hydrogen must be used, and vehicle efficiency through improved gas mileage must increase. Energy security means a reliable affordable energy supply. Congestion relief will require technological improvements to transportation like automated vehicles and roadways. The economy is a main driver, as consumers seek affordable mobility. The automobile of 2035 will likely use traditional and new fuels, and could see widespread electric vehicle fast charging and hydrogen refueling, as well as