CA Veh Code Section 23110

(a)

Any person who throws any substance at a vehicle or any occupant thereof on a highway is guilty of a misdemeanor.

(b)

Any person who with intent to do great bodily injury maliciously and willfully throws or projects any rock, brick, bottle, metal or other missile, or projects any other substance capable of doing serious bodily harm at such vehicle or occupant thereof is guilty of a felony and upon conviction shall be punished by imprisonment in the state prison.