There are three reasons to get a smog check.
• Registration Renewal: Every two years on most vehicles you are required to get a smog check to renew your registration with D.M.V. Gasoline vehicles newer than 6 years old, hybrids, motorcycles, gasoline vehicles 1975 or older, and diesel vehicles 1997 and older are exempt from this requirement.
• Change of Ownership Most vehicles need a smog check when they are bought or sold. Gasoline vehicles newer than 4 years old, hybrids, motorcycles, gasoline vehicles 1975 or older, and diesel vehicles 1997 and older are exempt from this requirement. Also, transfer of title between certain family members does not require a smog check.
• Bringing in a car from out of state most cars coming from out of state seeking registration in California need to be smogged. Motorcycles, gasoline vehicles 1975 or older, and diesel vehicles 1997 and older are exempt from this requirement.