Only for official purposes which include transportation:

(a) Between places of official business;

(b) Between such places and places of temporary lodging when public transportation is unavailable or its use is impractical;

(c) Between either paragraph (a) or (b) of this section and restaurants, drug stores, barber shops, places of worship, cleaning establishments, and similar places necessary for the sustenance, comfort, or health of the employee to foster the continued efficient performance of Government business; or

(d) As otherwise authorized by your agency under 31 U.S.C. 1344.