The California Department of Motor Vehicles (DMV) has jurisdiction over any business selling vehicles and requires licensure of that business. They also have forms and information on buying a vehicle from or selling to a private party. A smog check may be needed. The DMV's Notice of Transfer and Release of Liability will protect consumers from liability when buying or selling a car.
DMV does not regulate sales between private parties. Disputes arising from private party sales are a civil matter.
Department of Motor Vehicles
Safecar.gov, a web site of the National Highway Traffic Safety Administration, covers crash tests, five-star safety ratings, safety features, and recalls. The agency also maintains a toll-free Vehicle Safety Hotline to receive complaints and provide information on vehicle safety recalls.
(800) 424-9153 TTY