The automobile is a key artifact for understanding the relationship between technology and society. As it has developed into a mass-produced and mass-consumed commodity, it has played an increasing role in social life and its built environments. In its most exaggerated manifestation, in parts of the United States, the car is a singular transport mode for expansive urban regions. This social formation, often referred to as "urban sprawl," has been cited for its environmental and energy impact. Here, the focus is on its social structural impact on motorists as well as on nonmotorists. The auto is a prime example of how material technologies have dynamic and reciprocal relationships with their social contexts. These relationships raise significant ethical issues with regard to the development and application of technology.