41 CFR 102-34.230 - How am I responsible for protecting Government motor vehicles?
When a Government motor vehicle is under your control, you must:
(a) Park or store the Government motor vehicle in a manner that reasonably protects it from theft or damage; and
(b) Lock the unattended Government motor vehicle. (The only exception to this requirement is when fire regulations or other directives prohibit locking motor vehicles in closed buildings or enclosures.)