California administrative law approved the regulation “ARTICLE 6”. This law states that “warnings must be denoted for the purpose of renter prior to the renter’s use of the Vehicle, using one or more of the following methods:”

1. The warning is printed in the rental agreement or on the rental ticket jacket.
2. The warning is provided on a hang tag which is hung from the rear view mirror in the rental vehicle.
3. The warning is provided on a sign, in no smaller than 22-point type size, that is posted at the counter or similar area of the rental facility where rental transactions occur, where it will be likely to be seen, read, and understood by the renter during the process of renting the vehicle.
4. The warning is provided in an electronic rental contract.
5. The warning is provided in a confirmation email that is sent to the renter’s email address.
6. The warning is provided through a clearly marked hyperlink using the word “WARNING” on the on-line reservation page, or by otherwise prominently displaying the warning to the renter prior to completing the on-line reservation.

Reference: https://oehha.ca.gov/proposition-65/crnr/notice-amendments-article-6-clear-and-reasonable-warnings-rental-vehicle