States differ widely on punishments for joyriding. Some states consider joyriding as a less serious offense than theft, while others punish it the same as vehicle theft. A joyrider could be looking at probation, jail time, or even prison.
Merely riding in a stolen car, without more, cannot result in a criminal conviction. However, a person who rides in a stolen car knowing that the car has been stolen (or under circumstances where the passenger should have known that the car was stolen) could be convicted of a crime, as can any person
California has two different statutes that criminalize auto theft. The biggest difference is whether the defendant intends to take the car temporarily or permanently. Each crime may be punished as a misdemeanor or a felony.