California Code, Public Contract Code - PCC § 10295.2

(a) No vehicle acquisition request, vehicle purchase order, or new contract shall be approved by the Department of General Services for the purchase of new vehicles that would result in the expenditure of funds unless a certification is received in writing and signed by the secretary or director of an agency or a department, respectively, or his or her designee, that has requested the acquisition of the new vehicles, verifying that the purchase is vital and mission critical for the agency or department.

(b) The certification shall include the date, title, and the signature of the person authorizing the purchase.