Cal. Civil Code § 1939.03

Except as limited by Section 1939.05, a rental company and a renter may agree that the renter will be responsible for no more than all of the following: (a) Physical or mechanical damage to the rented vehicle up to its fair market value, as determined in the customary market for the sale of that vehicle, resulting from collision regardless of the cause of the damage. (b) (1) Loss due to theft of the rented vehicle up to its fair market value, as determined in the customary market for the sale of that vehicle, provided that the rental company establishes by clear and convincing evidence that the renter or the authorized driver failed to exercise ordinary care while in possession of the vehicle. In addition, the renter shall be presumed to have no liability for any loss due to theft if both of the following conditions are met: (A) An authorized driver returns the ignition key furnished by the rental company. (B) An authorized driver files an official report of the theft with the police or other law enforcement agency within 24 hours of learning of the theft and reasonably cooperates with the rental company and the police or other law enforcement agency in providing information concerning the theft. (2) The presumption set forth in this subdivision is a presumption affecting the burden of proof which the rental company may rebut by establishing that an authorized driver committed, or aided and abetted the commission of, the theft. (c) Physical damage to the rented vehicle up to its fair market value, as determined in the customary market for the sale of that vehicle, resulting from vandalism occurring after, or in connection with, the theft of the rented vehicle. However, the renter shall have no liability for any damage due to vandalism if the renter would have no liability for theft pursuant to subdivision (b). (d) Physical damage to the rented vehicle up to a total of five hundred dollars ($500) resulting from vandalism unrelated to the theft of the rented vehicle. (e) Actual charges for towing, storage, and impound fees paid by the rental company if the renter is liable for damage or loss. (f) An administrative charge, which shall include the cost of appraisal and all other costs and expenses incident to the damage, loss, repair, or replacement of the rented vehicle.