Legal Question in Criminal Law in California

I can't really answer the question without more information. In part it depends what you were arrested for. For example if you were arrested for driving without a license they may be able to keep the car for 45 days.. If the car is needed for evidence they can keep it until after your case is over. If the car was not registered they can keep it until it is registered. There are many other possibilities depending on what the charges are, who is the owner of the car, etc.

They can insist upon proof of registration before releasing it and they can insist that a licensed driver pick it up. They can also insist that you pay storage fees before they release it and these can be significant. In any case pick it up as soon as it is releasable in order to keep the storage fees from increasing.