In addition to those exemptions contained in Part 1 of Division 2 of the California Revenue and Taxation Code which are incorporated into this article by reference, there shall be excluded from the computation of the tax the sales price of:
(1) Purchases made by the State of California or by any agency, department, political subdivision, district or municipal corporation thereof.
(2) (None)
(3) (None)
(4) Purchases of motor vehicle fuel, the distribution of which in the State of California is subject to the tax imposed by Part 2 of Division 2 of the California Revenue and Taxation Code, except that users of motor vehicle fuel on which the motor vehicle fuel tax is refunded shall be liable for the tax impose by this article at the time and in the manner herein provided.