Cal. RTC § 6367

There are exempted from the taxes imposed by this part the gross receipts from occasional sales of tangible personal property and the storage, use, or other consumption in this state of tangible personal property, the transfer of which to the purchaser is an occasional sale. This exemption does not apply to the gross receipts from the sale of, or to the storage, use, or other consumption in this state of, a mobilehome or commercial coach required to be annually registered under the Health and Safety Code, a vessel or aircraft, as defined in Article 1 (commencing with Section 6271) of Chapter 3.5 of this part, or a vehicle required to be registered under the Vehicle Code or a vehicle required to be identified under Division 16.5 (commencing with Section 38000) of the Vehicle Code or a vehicle that qualifies under the permanent trailer identification plate program pursuant to subdivision (a) of Section 5014.1 of the Vehicle Code. This section shall not preclude the exemption afforded under Section 6281.