Take it from Goldilocks: your paper topic should not be too big or too small. If it's too big, you'll be writing forever. If it's too small, you won't find enough research to support your ideas. Using the 5Ws (Who, What, Where, Why, When) to form a thesis that is just right.
Narrow your topic using the 5 W's.
Who? / What?
Focus on one specific aspect or event: Liability issues in driverless car fatalities.
Where?
Focus on one geographic area: Driverless cars on California roadways.
Why?
Focus on one problem or question: Effect of driverless cars on the transportation industry.
When?
Focus on one time period: Advances in driverless car technology in 2016.