California Code, Health and Safety Code - HSC § 18066.5

If a purchaser of a manufactured home, mobilehome, or commercial coach pays to the dealer an amount for transfer of title of the manufactured home, mobilehome, or commercial coach, which amount is in excess of the actual fees due for the transfer, or which amount is in excess of the amount which has been paid, prior to the sale, by the dealer to the state in order to avoid penalties that would have accrued because of late payment of the fees, the dealer shall return the excess amount to the purchaser, whether or not the purchaser requests the return of the excess amount.