From Consumer Wiki
The U.S. Department of Transportation established the National Highway Traffic Safety Administration (NHTSA), so information on all vehicle safety related issues on cars, trucks, and motor vehicle equipment would be available to consumers. NHTSA accepts complaints on auto safety issues.
National Highway Traffic Safety Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
The Center for Auto Safety (CAS) is a nonprofit organization which works to reduce accidents due to unsafe vehicles and promote reliability and quality. The Center will take complaints and will research and document any history of unreliability with an automobile and make that information available to consumers. In addition, CAS will refer a consumer to legal specialists for litigation if requested.
Center for Auto Safety (CAS)
1825 Connecticut Avenue, NW Suite 330
Washington, DC 20009
The California Department of Motor Vehicles (DMV) will review any complaint about car dealers selling unsafe used vehicles or used vehicles with defects. Any safety issue complaint related to brakes should be referred to the California Highway Patrol (CHP), but DMV is responsible for the following other areas: bumpers, exhaust, muffler, horns, lights, safety belts, tires, windshields, mirrors, or wipers. Complaints about new automobiles should be directed to the New Motor Vehicles Board.
DMV - Investigations Unit
California Highway Patrol
PO Box 942898
Sacramento, CA 95814