Cal. Bus. & Prof. Code § 7507.12

With regard to collateral subject to registration under the Vehicle Code, a repossession is complete when the repossessor gains entry to the collateral or when the collateral becomes connected to a tow truck or the repossessor’s tow vehicle, as those terms are defined in Section 615 of the Vehicle Code. No person other than the legal owner may direct a repossessor to release a vehicle without legal authority to do so.