From Consumer Wiki
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