This paper provides a long-term view of the deployment of environmental technologies for light-duty vehicles in the United States and their implications for other vehicle attributes. It considers technologies for controlling tropospheric air pollutants, improving fuel economy, and reducing corollary greenhouse gas emissions. Since the introduction of the first controls to improve ambient air quality in the early 1960s, these technologies have gone from simple crankcase vapor recirculation and positive control valve systems and adjustments in carburetor air/fuel ratio and spark timing to systems that continuously control and monitor vehicle operations to optimize emissions reductions and fuel economy. Not only have these technologies produced major benefits for public health, the environment, and energy conservation, but they have also fundamentally altered the characteristics of the vehicles we drive today. And future regulations will reform the vehicle fleet even further. During the next 50 years, new vehicles will continue to be more fuel efficient, weigh less, be safer, emit fewer air pollutants, and cost more to purchase than current vehicles. These vehicles will also be less expensive to fuel and will have increased autonomy and consumer features. The impact of future regulatory demands is a continuation of a long-term regulatory trend toward a safer, cleaner, and more efficient vehicle fleet.This paper relies in part on the vehicle-related reports developed by the National Academies of Sciences, Engineering, and Medicine for the U.S. Departments of Energy and Transportation and for the U.S. Environmental Protection Agency. The Academies are often called upon by federal agencies and by Congress to weigh in on critical science, technology, and policy issues, and the regulation of light-duty vehicles has been a long-term topic of interest of its sponsors. This paper also relies on the extensive set of materials reviewed during the course of Academies’ studies.