Cal. Rev. & Tax. Code § 6018.8

The Department of Transportation is a consumer of, and shall not be considered a retailer within the provisions of this part with respect to, passenger transportation vehicles, including, but not limited to, rail passenger cars, locomotives, other rail vehicles, bus and van fleets, and ferryboats, which it sells to and leases back from any person pursuant to Article 4 (commencing with Section 14060) of Chapter 1 of Part 5 of Division 3 of Title 2 of the Government Code.